John C Hagan III, MD, FACS, FAAO  
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Jul 14, 2011 - 4 comments


Utility Values Associated With Vitreous Floaters
Ajeet M. Wagle
AffiliationsDepartment of Ophthalmology and Visual Sciences, Khoo Teck Puat Hospital, SingaporeDepartment of Ophthalmology and Visual Sciences, Alexandra Hospital, SingaporeEye Clinic, Jurong Medical Center, SingaporeFaculty of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, SingaporeInquiries to Ajeet M. Wagle, Department of Ophthalmology and Visual Sciences, Khoo Teck Puat Hospital, 90 Yishun Central, Singapore 768828
, Wei-Yen Lim
AffiliationsDivision of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
, Tiong-Peng Yap
AffiliationsDepartment of Ophthalmology and Visual Sciences, Alexandra Hospital, Singapore
, Kumari Neelam
AffiliationsDepartment of Ophthalmology and Visual Sciences, Khoo Teck Puat Hospital, SingaporeDepartment of Ophthalmology and Visual Sciences, Alexandra Hospital, SingaporeEye Clinic, Jurong Medical Center, Singapore
, Kah-Guan Au Eong

To ascertain the health-related quality of life associated with symptomatic degenerative vitreous floaters.

Cross-sectional questionnaire survey.

In this institution-based study, 311 outpatients aged 21 years and older who presented with symptoms of floaters were enrolled. Data from 266 patients (85.5%) who completed the questionnaire were analyzed. Utility values were assessed using a standardized utility value questionnaire. The time trade-off (TTO) and standard gamble (SG) for death and blindness techniques were used to calculate the utility values. Descriptive, univariate, and multivariate analyses were performed using Stata Release 6.0.

The mean age of the study population was 52.9 ± 12.02 years (range, 21–97). The mean utility values were 0.89, 0.89, and 0.93 for TTO, SG (death), and SG (blindness), respectively. Patients aged ≤55 years reported significantly lower SG (blindness) utility values when compared with patients above 55 years of age (age ≤55 = 0.92, age >55 = 0.94, P = .007). Utility measurements did not demonstrate significant relationship with any of the other socio-demographic variables examined in this study. The utility values did not demonstrate any significant relationship with other ocular characteristics such as duration of symptoms, presence of a posterior vitreous detachment, and presence or severity of myopia.

Symptomatic degenerative vitreous floaters have a negative impact on health-related quality of life. Younger symptomatic patients are more likely to take a risk of blindness to get rid of the floaters than older patients.

Floaters are entoptic images of opacities in the vitreous cavity that usually occur as a result of degenerative changes in the vitreous gel such as vitreous syneresis, condensation of vitreous fibers, and posterior vitreous detachment (PVD).1, 2, 3 Degenerative vitreous floaters may become asymptomatic with passage of time. However, in some patients, symptomatic degenerative vitreous floaters persist for many years and can potentially affect health-related quality of life in several ways. Floaters can result in intermittent blurred vision, glare and haze attributable to migration of vitreous opacities into the visual axis, and interference with important activities of daily living such as reading, driving, and near work.3

Individuals with symptomatic degenerative floaters constitute a fair proportion of patients seen in ophthalmology clinics in Singapore. Myopia, which is often associated with degenerative floaters, is a growing public health problem with high prevalence rates in Singapore.3, 4, 5 The health-related quality of life associated with floaters is not well understood. Of note, Snellen acuity, the standard test of visual function in a clinical setting, is unable to quantify visual disability associated with vitreous floaters on day-to-day functioning and overall quality of life.1, 3, 6 Although surgical interventions such as Nd:YAG laser vitreolysis, deep anterior vitrectomy combined with cataract surgery, and pars plana vitrectomy are available, they have been offered to patients with symptomatic floaters only rarely.1, 3, 6

Health-related quality of life is playing a vital role in every specialty of medicine because of the increasing importance of patient preferences and escalating healthcare costs. Utility values, originally described by Von Neumann and Morganstern in 1940, allow an objective quantification of the functional quality of life associated with a specific disease state.7, 8, 9 By convention, a utility value of 1.0 implies a perfect health state whereas a value of 0.0 indicates the worst possible health state or death. The closer the value is to 1.0, the better is the perceived health-related quality of life. Currently, utility values modified by Brown and associates are used for measuring health-related quality of life in patients with eye diseases.10 Utility values are measured using a number of techniques. The time trade-off (TTO) and standard gamble (SG) methods represent 2 common techniques of eliciting preferences under the utility theory. The TTO utility measures the numbers of years of remaining life that an individual is willing to trade off for a hypothetical technology that restores perfect vision, whereas the SG utility assesses the risks associated with a hypothetical technology that the patient is willing to take to return to the perfect health state.

Utility values have been measured for a variety of eye diseases that affect health-related quality of life such as diabetic retinopathy, age-related macular degeneration, glaucoma, and myopia.9, 11, 12, 13, 14, 15 Understanding the impact of floaters on the overall health-related quality of life can be invaluable in deciding possible treatment options in specific subgroups of patients. In this study, we assess the utility values in patients presenting primarily with a history of floaters.

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In this questionnaire-based study, we enrolled consecutive patients presenting primarily with a history of floaters to the Department of Ophthalmology and Visual Sciences in Alexandra Hospital, Singapore, from April 1, 2006 to December 31, 2007.

Patients were eligible to participate in the study if they satisfied the following criteria: age 21 years and above, history of floaters in 1 or both eyes, best-corrected visual acuity (BCVA) better than 20/30 in the better-seeing eye, no significant coexisting retinal pathology, and willingness to give an informed consent. Patients with acute-onset floaters (defined as floaters of less than 4 weeks' duration), and high myopia (spherical equivalent equal to or greater than −6.0 diopters [D]) were also included in the study. Patients with floaters secondary to other eye conditions such as vitreous hemorrhage, vitreous inflammation, and ocular trauma were excluded from the study. Similarly, patients with dense corneal or lenticular opacities that hindered optimal visualization of the fundus or those with concomitant ocular diseases resulting in loss of vision were not eligible to participate in the study. Lastly, patients were not enrolled if they were unwilling to answer and/or unable to understand utility value questionnaires because of psychiatric problems or dementia.

A comprehensive eye examination including Snellen BCVA, slit-lamp biomicroscopy, and a dilated fundus examination using indirect ophthalmoscopy was performed for each patient. Additionally, in all participants, demographic and socioeconomic data, such as age, gender, ethnicity, educational status, occupation, housing, personal and family income, and total number of family members, were recorded.

A single trained research assistant interviewed the patients using a standardized utility value questionnaire.11, 12, 15 Where necessary, the questionnaire was interpreted by the interviewer in the patients' preferred language. During the face-to-face interviews, the research assistant encouraged the patients to ask questions if they were unable to comprehend the utility questionnaire.

Utility values were calculated using the commonly used techniques of TTO and SG for death and blindness. TTO utility value was calculated based on the time traded in years over the expected number of years of the respondent's remaining life that he/she is willing to give up for a hypothetical technology to restore perfect health (TTO utility = 1 – [time traded in years/estimated number of years of remaining life]). Standard gamble utility was calculated as the amount of risk (in percentage) of death or blindness that a respondent is willing to take for a hypothetical technology that may restore perfect vision respectively (SG utility = 1 – [amount of risk of death or blindness in percentage that the respondent is willing to take/100]).

Data Analysis
Descriptive, univariate, and multivariate analyses were performed using Stata Release 6.0 (Stata Corporation, College Station, Texas, USA). The mean and median TTO, SG (death), and SG (blindness) utilities were calculated for all patients with floaters. Utility values were compared across different age groups, socio-demographic groups, and patients' presentation characteristics using the Wilcoxon rank sum test and Kruskal-Wallis test. These nonparametric tests were used for statistical analysis because the normality assumption needed for parametric tests was not satisfied by our sample. All P values quoted are 2-sided and considered statistically significant when the values are below .05. Multiple linear regression analysis was performed after adjusting for the effect of confounding factors.

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In this cross-sectional study, 311 consecutive patients presenting primarily with a history of floaters were enrolled. Of these, data from 266 patients (85.5%) who completed the questionnaire were analyzed. The details of demographic and socioeconomic characteristics are presented in Table 1.

TABLE 1. Demographic and Socioeconomic Characteristics of Study Population With Symptomatic Degenerative Vitreous Floaters (N = 266)
Demographic Characteristics Number (%)
Mean age (range), years 52.9±12.02(21–97)
Sex ratio (male:female) 0.78:1
Chinese (%) 239(89.9%)
Non-Chinese (%) 37(10.1%)
Housing type  
Public housing estates 215(81.4%)
Private housing 49(18.6%)
Education status  
No formal education/primary education 51(19.3%)
Secondary education 119(44.9%)
Tertiary education 95(35.8%)
Average number of family members (range) 3.48(1-7)
Employment status (%)  
Employed 174(65.9%)
Unemployed/retired 90(34.1%)
Average monthly income (USD)  
Personal 1665
Family 2371
USD = United States dollars.

Utility Values
The mean utility values for our study population were 0.89, 0.89, and 0.93 for TTO, SG (death), and SG (blindness), respectively.

Utility Values and Demographics
The details of utility values associated with various demographic factors are shown in Table 2. Time trade-off and SG (death) utility values did not differ significantly with age in patients with floaters (TTO: age ≤55 = 0.89, age >55 = 0.89, P = .16; SG [death]: age ≤55 = 0.88, age >55 = 0.90, P = .07). However, patients aged ≤55 years reported lower SG (blindness) utility values when compared with patients >55 years of age (age ≤55 = 0.92, age >55 = 0.94, P = .007).

TABLE 2. Utility Values Associated With Various Demographic and Socioeconomic Factors in Patients With Symptomatic Degenerative Vitreous Floaters
Characteristic n TTO Mean (Median) P Value n SG (Death) Mean (Median) P Value n SG (Blindness) Mean (Median) P Value
All 266 0.89(1.00)  266 0.89(1.00)  266 0.93(1.00)  
Age   .16   .07   .007a
≤55 years 146 0.89(0.96)  146 0.88(1)  146 0.92(1)  
>55 years 120 0.89(1)  120 0.90(1)  120 0.94(1)  
Gender   .52   .20   .39
Male 117 0.89(1)  117 0.88(1)  117 0.92(1)  
Female 149 0.90(1)  149 0.89(1)  149 0.94(1)  
Race   .57   .26   .54
Chinese 239 0.89(1)  239 0.88(1)  239 0.93(1)  
Non-Chinese 27 0.92(1)  27 0.92(1)  27 0.92(1)  
Personal income   .26   .29   .65
No income 121 0.90(1)  121 0.89(1)  121 0.93(1)  
US$ 1–1333.3 62 0.87(0.9)  62 0.86(1)  62 0.94(1)  
US$ >1333.3 83 0.90(1)  83 0.90(1)  83 0.91(1)  
Household income   .57   .77   .46
No income 113 0.89(1)  113 0.88(1)  113 0.93(1)  
US$ 1–1333.3 78 0.89(0.953)  78 0.90(1)  78 0.94(1)  
US$ >1333.3 75 0.90(1)  75 0.89(1)  75 0.92(1)  
Education   .13   .93   .59
No formal education/primary education 51 0.92(1)  51 0.87(1)  51 0.91(1)  
Secondary education 119 0.87(1)  119 0.88(1)  119 0.93(1)  
Diploma/degree 95 0.90(1)  95 0.91(1)  95 0.95(1)  
Housing type   .44   .46   .57
Public (1–4 room flats) 120 0.88(1)  120 0.90(1)  120 0.92(1)  
Public (>5 room flats) 95 0.89(1)  95 0.87(1)  95 0.93(1)  
Private 49 0.91(1)  49 0.90(1)  49 0.96(1)  
Occupation   .13   .19   .48
Employed/student 174 0.89(1)  174 0.88(1)  174 0.93(1)  
Housewife/retired/non-employed 90 0.90(1)  90 0.90(1)  90 0.93(1)  
SG = Standard gamble; TTO = time trade-off; US$ = United States dollar (1 US$ = 1.50 Singapore $).

aSignificant P value 1 month 124 0.90(1)  124 0.89(1)  124 0.93(1)  
Laterality of presentation   .89   .36   .75
Unilateral 113 0.89(1)  113 0.89(1)  113 0.93(1)  
Bilateral 153 0.90(1)  153 0.89(1)  153 0.9391)  
Myopia   .55   .26   .92
No myopia 107 0.90(1)  107 0.86(1)  107 0.91(1)  
Myopia in at least 1 eye 159 0.89(1)  159 0.90(1)  159 0.95(1)  
Severity of myopia   .41   .35   .58
SE less than −6.0 D 100 0.92(1.00)  115 0.92(1.00)  116 0.94(1.00)  
SE greater than or equal to −6.0 D 59 0.88(0.96)  64 0.88(1.00)  67 0.95(1.00)  
PVD   .79   .57   .42
Absent 131 0.90(1)  131 0.90(1)  131 0.93(1)  
Present 135 0.88(1)  135 0.88(1)  135 0.93(1)  
D = diopter; PVD = posterior vitreous detachment; SE = spherical equivalent; SG = standard gamble; TTO = time trade-off.

Utility Values and Acute-Onset Floaters
The mean (± SD) duration of presence of vitreous floaters was 54.8 ± 6.12 weeks, ranging from 1 week to 5 years and 10 months (300 weeks). Acute-onset floaters were noted in 142 of the 266 patients (53.4%). Patients with acute-onset floaters did not report significantly different utility values from patients with long-standing symptomatic floaters (TTO: acute-onset floaters = 0.88, long-standing floaters = 0.90, P = .34; SG [death]: acute-onset floaters = 0.89, long-standing floaters = 0.89, P = .90; SG [blindness]: acute-onset floaters = 0.93, long-standing floaters = 0.93, P = .81).

Utility Values and Bilateral Floaters
A history of bilateral vitreous floaters was present in 153 of 266 patients (57.5%). Patients with bilateral floaters did not demonstrate significantly different utility values from those having unilateral vitreous floaters (TTO: unilateral = 0.89, bilateral = 0.90, P = .89; SG [death]: unilateral = 0.89, bilateral = 0.89, P = .36; SG [blindness]: unilateral = 0.93, bilateral = 0.93, P = .75).

Utility Values and Myopia
The prevalence of myopia, defined as spherical equivalent greater than −0.5 D in at least 1 eye, in our study population was 60% (159/266), with a third (59/159, 37%) of these patients having high myopia. Utility values did not differ significantly with presence or absence of myopia in patients with vitreous floaters (TTO: myopia present = 0.90, myopia absent = 0.89, P = .55; SG [death]: myopia present = 0.86, myopia absent = 0.90, P = .26; SG [blindness]: myopia present = 0.91, myopia absent = 0.95, P = .92). The severity of myopia also did not show a significant relationship with utility values (TTO: myopia equal to or higher than −6.0 D = 0.88, myopia lower than −6.0 D = 0.90, P = .41; SG [death]: myopia equal to or higher than −6.0 D = 0.88, myopia lower than −6.0 D = 0.92, P = .35; SG [blindness]: myopia equal to or higher than −6.0 D = 0.95, myopia lower than −6.0 D = 0.94, P = .58).

Utility Values and Posterior Vitreous Detachment
A PVD was observed in 135 of 266 patients (50.7%). The presence of PVD did not affect utility values significantly (TTO: PVD present = 0.90, PVD absent = 0.88, P = .79; SG [death]: PVD present = 0.90, PVD absent = 0.88, P = .57; SG [blindness]: PVD present = 0.93, PVD absent = 0.93, P = .42).

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In this study, we assessed the health-related quality of life in 266 patients presenting primarily with a history of floaters using utility values. The results suggest that degenerative floaters have a negative impact on the health-related quality of life. Younger patients with symptomatic floaters exhibit relatively lower utility values for SG (blindness) when compared with elderly symptomatic patients.

Patients with floaters are willing to trade off an average 1.1 years out of every 10 years of their remaining life to get rid of the symptoms associated with floaters. Furthermore, these patients are willing to take, on average, an 11% risk of death and a 7% risk of blindness to get rid of symptoms relating to floaters. The mean utility values for patients with floaters are comparable to the utilities reported by patients with other eye diseases such as age-related macular degeneration, diabetic retinopathy, and myopia with similar visual acuity (visual acuity of 20/20 to 20/25) (Table 4). 9, 11, 12, 13, 14, 15 Interestingly, the mean TTO utility value for floaters is also comparable to TTO values reported for many other systemic diseases and health states such as hypertension, mild angina, mild stroke, colon cancer, and asymptomatic HIV infection (Table 5).8, 16, 17, 18, 19 Although floaters do not seem to affect quality of life to the same degree as more severe forms of ocular and systemic diseases, their impact is nevertheless noteworthy.

TABLE 4. Comparison of Utility Values for Symptomatic Degenerative Vitreous Floaters With Other Ocular Diseases and Health States
Ocular Disease/Health State TTO SG (Death) SG (Blindness)
Floaters 0.89 0.89 0.93
1. In teenage school students15 0.93 — 0.85
2. In medical students9 0.97 0.99 —
Glaucoma13 0.88 0.94 0.95
Diabetic retinopathy12 (BCVA 20/20 to 20/25) 0.85 0.88 —
Age-related macular degeneration11 (BCVA 20/20 to 20/25) 0.89 0.96 —
BCVA = best-corrected visual acuity in the better eye; SG = standard gamble; TTO = time trade-off.

TABLE 5. Comparison of Time Trade-off Utility Values for Symptomatic Degenerative Vitreous Floaters With Other Systemic Diseases
Systemic Disease/Health State TTO Utility
Floaters 0.89
Hypertension16 0.98
Mild angina8 0.87
Mild stroke17 0.87
Colon cancer18 0.88
Asymptomatic HIV infection19 0.87
HIV = human immunodeficiency virus; TTO = time trade-off.

Similar to other studies, we observed overall higher utility values for SG (blindness) when compared to the TTO and SG (death) values in our study population. This shows that compared to trading years of remaining life for a better health-related quality of life or taking a risk for immediate death, individuals are less willing to take a risk of blindness. This risk aversion with the SG technique has been reported by past studies investigating utility values in eye diseases.9

In our study population, younger patients (21–55 years) with symptomatic floaters were willing to take a relatively higher risk of blindness to get rid of floaters when compared with elderly patients (>55 years). Two previous studies have proposed that the higher utility values observed in teenage students (15-18 years) with myopia, in contrast with adults, suggests that students are less willing to take risks in return for perfect vision than adults because of differences in value of impact of the eye disease and life expectancy.15 Our finding suggests that younger patients, who belong to the economically active group, are more keen and less risk-averse to improve their health-related quality of life by opting for a therapeutic intervention to remove their floaters. This subgroup of patients may benefit from current treatment options to improve their health-related quality of life. The elderly symptomatic patients may have reported a relatively higher SG (blindness) utility value due to risk aversion when compared with younger patients.

We failed to observe a significant relationship between utility values and the socioeconomic variables. Results of previous studies that have investigated the relationship between socioeconomic variables and utility values in various eye diseases have been inconsistent. For instance, of the 4 studies that have examined the relationship between educational status and utility values in patients with eye diseases, 2 have failed to demonstrate a significant relationship between level of education and utility values.9, 11, 15, 18

We compared the utility values in patients with acute-onset floaters with those having long-standing floaters and did not find any significant difference in their utility values. This is similar to the findings of Brown and associates, which showed that duration of disease did not affect utility measurements in patients with age-related macular degeneration.11

Floaters are commonly reported in eyes with myopia. In our study, 59.7% of patients had myopia, with about a third of them having high myopia. Myopia itself is also known to affect quality of life.9, 15 Vitreous floaters are often perceived much earlier in myopic eyes as vitreous syneresis and PVD tends to occur at a younger age in these eyes.3, 4 The retinal magnification of the images associated with myopia also makes the symptom more pronounced. As myopia is a growing public health problem with high prevalence rates especially in several southeast Asian countries,5 the prevalence of patients with symptomatic floaters is likely to increase. This prompted us to compare the utility values associated with floaters in patients with and without myopia; however, we failed to demonstrate a significant relationship between utility values and presence (degree) of myopia in patients with floaters. Two previous studies have also shown no significant difference in utility values with different severity of myopia.9, 15

We are aware of certain potential limitations of our study. First, the results of this study may not truly reflect the impact of floaters on specific vision-related tasks because we did not use a vision-specific quality-of-life questionnaire. Second, we did not examine the relationship between utility values and detailed characteristics of vitreous floaters, such as number, size, and density of floaters as well as the area of visual field involved by the floaters. Other potential limitations that would preclude generalizing our study results are a relatively small sample size, a single-center study, and a predominantly Chinese study population.

In conclusion, symptomatic degenerative vitreous floaters have an impact on the health-related quality of life. Young symptomatic patients are more likely to take a risk of blindness to get rid of floaters.

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Publication of this article was funded by a National Healthcare Group – Small Investigator Grant, Singapore (NHG-SIG I/06/034). The funding organization had no role in the design and conduct of the research. The authors have no financial interests to disclose. Involved in design and conduct of the study (A.M.W., T.P.Y., K.G.A.E.); collection, management, analysis, and interpretation of the data (A.M.W., W.Y.L.); and preparation, review, or approval of the manuscript (A.M.W., W.Y.L., T.P.Y., K.N., K.G.A.E.). This study and the data accumulation were carried out with ethics approval from the Domain Specific Review Board of the National Healthcare Group, Singapore. Informed consent for the research was obtained from the patients. The study was conducted in adherence to the tenets of the Declaration of Helsinki and was HIPAA compliant.

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1.Mossa F, Delaney YM, Rosen PH, Rahman R. Floaterectomy: combined phacoemulsification and deep anterior vitrectomy. J Cataract Refract Surg. 2002;28(4):589–592
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12.Brown MM, Brown GC, Sharma S, Shah G. Utility values and diabetic retinopathy. Am J Ophthalmol. 1999;128(3):324–330
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14.Brown MM, Brown GC, Sharma S, Landy J. Quality of life and visual loss from diabetic retinopathy and age-related macular degeneration. Arch Ophthalmol. 2002;120(4):489–484
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Ajeet M. Wagle is a Consultant Ophthalmologist at the Department of Ophthalmology & Visual Sciences at Khoo Teck Puat Hospital, Singapore. He specializes in the management of diseases of the vitreous and retina. Besides clincal work, he has keen interests in clinical research. He is a teaching faculty at the Faculty of Medicine, Yong Loo Lin School of Medicine, National University of Singapore and the Singapore Polytechnic Optometry Centre.

See Accompanying Editorial on page Dr. John Hagan's Blog

PII: S0002-9394(11)00064-X


© 2011 Elsevier Inc. All rights reserved.


Jul 14, 2011 - 42 comments

FROM: John C. Hagan III MD, FACS, FAAO   This is a reprint of an editorial in the July 2011 American Journal of Ophthalmology and represents the latest information on floaters. It references a second article from the same issue which I will also post.


In 1976, Dr Ernst Wynder, founding president of the American Health Foundation and founding editor of the journal Preventive Medicine, stated that “It should be the function of medicine to help people die young…as late in life as possible.”1 However, medicine in general, and ophthalmology in specific, are disease-oriented disciplines. In the former case, this is due to the fact that “Disease is a living experience for the man of flesh and bone. In contrast, health is a disembodied concept. It stimulates no emotional response because it is an inhuman, fleshless abstraction” (René Jules Dubos, The Silliman Lectures, Yale, 1965).1 As ophthalmologists, we are trained to evaluate eyes by seeking evidence of disease using biomicroscopy and ophthalmoscopy, as well as with diagnostic testing. When we rule out pathology by these modalities, we advise patients that they are free of disease. Such advice is apparently a frustrating and unfulfilling experience for patients with “floaters.” From their point of view, the consulting ophthalmologist who sought evidence of disease and found none has nonetheless failed to address their health and quality-of-life issues.

In youth, vitreous is a solid and clear gel filling the center of the eye, firmly attached to the retina. The exquisite transparency of vitreous allows unhindered transmission of light to the retina for photoreception.2 Other than “exogenous” sources, such as hemorrhage and inflammation, there are 2 main causes of the entopic phenomenon called “floaters,” which result from light scattering by structures within the vitreous body and/or at the posterior vitreous cortex. Although devoid of liquid during infancy, the vitreous body begins to liquefy in childhood due to molecular rearrangement of the constituent macromolecules hyaluronan and collagen. Part of this molecular alteration involves cross-linking and aggregation of vitreous collagen fibrils. If advanced, fibrillar aggregation can cause sufficient interference of photon transmission to induce chronic and progressive floaters. In myopia, the process of vitreous gel liquefaction and fibrillar aggregation appears to be accelerated, a manifestation of myopic vitreopathy.3

Concurrent with vitreous gel liquefaction, there is weakening of vitreoretinal adhesion. When both processes advance in tandem to a critical threshold,2, 3 there is separation of the posterior vitreous cortex from the retina, perhaps initially only in the perifoveal region.4 Displacement of liquefied vitreous into the developing cleavage plane between the posterior vitreous cortex and the internal limiting lamina of the retina collapses the posterior vitreous away from the retina, an event called posterior vitreous detachment (PVD). While it has long been taught that PVD is abnormal, it may well be that PVD is the salubrious result of evolutionary progress. This concept arises from the growing awareness that in a variety of diseases, such as diabetic retinopathy5 and age-related macular degeneration6, 7 (AMD), PVD is a far safer condition. That notwithstanding, entopic phenomena resulting from this event induce acute floaters. These arise from the posterior vitreous cortex itself as well as tissue that is sometimes adherent to the posterior vitreous cortex, typically parapapillary fibro-glial in origin. When attributable to myopic vitreopathy,3 PVD occurs 10 to 15 years earlier in life.

The subjective experience of sudden floaters is very common after PVD. While many patients complain that this is bothersome, ophthalmologists tend to pay little heed to these symptoms other than to rule out anomalous PVD3, 8 manifesting as either peripheral or posterior retinal pathology. Once the absence of disease has been assured, the typical eye care professional ceases to be concerned about the issue of floaters. While the Hippocratic principle of “primum non nocere” has guided our approach to date, it may well be time to reexamine our perception that floaters are simply an innocuous, indeed curiously desirable, manifestation of the “normal” aging process.

In this issue of the Journal, Wagle and associates9 present fascinating new information concerning the utility value of floaters, as expressed by patients. Utility values allow an objective quantification of the functional quality of life associated with a specific “disease” state. A utility value of 1.0 implies a perfect “health” state, while death has a utility value of 0.0. The findings of this study indicate that the utility values of floaters are equal to AMD and lower than diabetic retinopathy and glaucoma. According to this study, floaters have lower utility values than mild angina, mild stroke, colon cancer, and asymptomatic HIV infection. This indicates that floaters have a significant negative impact on the quality of life as compared to ocular as well as systemic diseases. It is interesting to note that there was no difference between acute (less than 1 month) and chronic (mean duration of more than 1 year) floaters. This finding throws into question our long-held belief and oft-offered counsel to patients that their symptoms will lessen in severity, either due to settling of vitreous opacities below the optical axis or because of neuro-psychological adaptation. Surprisingly, the investigators claimed that 49.3% of the study group had no PVD. This is suspect, since subjects only underwent an examination and not diagnostic testing, such as ultrasound or optical coherence tomography. Furthermore, 56% of the subjects were women and 59.7% were myopic—both known to predispose to PVD. On the other hand, the authors appropriately point out that the retinal magnification of the images associated with myopia can make floaters seem more pronounced, perhaps explaining how a large number of subjects in this study complained of floaters in the absence of a PVD.

Most remarkably, the investigators of this study found that these patients were willing to take an 11% risk of death and a 7% risk of blindness to get rid of symptoms related to floaters. As the authors state, patients with floaters are willing to trade off 1.1 years out of every 10 years of their remaining lives to get rid of the symptoms of floaters. To some extent that explains the willingness of patients to undergo unproven attempts at mitigating their symptoms, such as YAG laser vitreolysis, for which there is no evidence of efficacy. Definitive treatment is available with vitrectomy, which has been rendered faster, less invasive, and safer by the advent of 25G instrumentation. Yet, there are small risks associated with this invasive procedure and in phakic patients there are lens-related considerations. To obviate the cost and risk (albeit small) of surgery, the future will likely see the development of drug therapy for floaters, via pharmacologic vitreolysis.10 Caution must be exercised, however, for some agents may induce or aggravate floaters as opposed to dissolve them.10, 11

Future advances in our ability to promote health and not just treat disease will depend upon a paradigm shift in philosophy and the development of technologies for health evaluation. We should first accept health as its own diagnosis1 and not just the absence of disease. Improving our understanding and management of conditions such as age-related vitreous degeneration,2, 3 diabetic vitreopathy,12 and myopic vitreopathy3 will then depend upon developing new diagnostic nanotechnologies, such as dynamic light scattering (DLS). This noninvasive, laser-based nano-detector is able to quantitate particle sizes in the cornea, lens, aqueous, and vitreous13 as small as 3 nm in diameter. DLS has been used to determine an alpha-crystallin index in 380 lenses of human eyes14 as well as demonstrate the effects of diabetic vitreopathy11 and pharmacologic vitreolysis.15, 16 In the meantime, however, we need to be aware of and sensitive to the fact that there continues to be a proliferation of floater websites on the internet and the formation of international floater organizations, as expressions of patient frustration with our inability or unwillingness to help them die young, as late in life as possible.

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The author indicates no funding support. The author has been a consultant to Pfizer, Shire, Storz, Alcon, ISTA, Vitreo-Retinal Technologies, and ThromboGenics, and is a shareholder in ThromboGenics, Ltd. The author (J.S.) is solely responsible for the conceptualization of this article; collection, management, analysis, and interpretation of data; and preparation, review, and approval of the manuscript.

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1.Sebag J. The diagnosis of health (First Prize, National Essay Competition). Preventive Medicine. 1979;8(1):76–78
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2.Sebag J. The Vitreous—Structure, Function and Pathobiology. New York: Springer-Verlag; 1989;
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3.Sebag J, Yee KMP. Vitreous—from biochemistry to clinical relevance. In:  Tasman W,  Jaeger EA editor. Duane's Foundations of Clinical Ophthalmology, Vol. 1. Philadelphia: Lippincott Williams & Wilkins; 2007;p. 1–67
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4.Johnson MW. Perifoveal vitreous detachment and its macular complications [thesis]. Trans Am Ophthalmol Soc. 2005;103:537–567
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5.Akiba J, Arzabe CW, Trempe CL. Posterior vitreous detachment and neovascularization in diabetic retinopathy. Ophthalmology. 1990;97(7):889–891
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6.Krebs I, Brannath W, Glittenberg K, et al. Posterior vitreo-macular adhesion: a potential risk factor for exudative age-related macular degeneration. Am J Ophthalmol. 2007;144(5):741–746
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7.Robison C, Krebs I, Binder S, et al. Vitreo-macular adhesion in active and end-stage age-related macular degeneration. Am J Ophthalmol. 2009;148(1):79–82
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8.Sebag J. Anomalous PVD—a unifying concept in vitreo-retinal diseases. Graefes Arch Clin Exp Ophthalmol. 2004;242(8):690–698
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9.Wagle AM, Lim W-Y, Yap T-P, Neelam K, Au Eong K-G. Utility values associated with vitreous floaters. Am J Ophthalmol. 2011;152(1):60–65
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10.Sebag J. Pharmacologic vitreolysis [guest editorial]. Retina. 1998;18(1):1–3
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11.Sebag J. Pharmacologic vitreolysis—premise and promise of the first decade [guest editorial]. Retina. 2009;29(7):871–874
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12.Sebag J. Diabetic vitreopathy [guest editorial]. Ophthalmology. 1996;103(2):205–206
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14.Datiles MB, Ansari RR, Suh KI, et al. Clinical detection of precataractous lens protein changes using dynamic light scattering. Arch Ophthalmol. 2008;126(12):1687–1693
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16.Sebag J, Ansari RR, Suh KI. Pharmacologic vitreolysis with microplasmin increases vitreous diffusion coefficients. Graefes Arch Clin Exp Ophthalmol. 2007;245(4):576–580
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A graduate of Columbia & Harvard, Jerry Sebag is considered a leading authority on vitreous. He is Founding Director of the VMR Institute in Huntington Beach, California (www.VMRinstitute.com), Professor of Clinical Ophthalmology at the Doheny Eye Institute of USC, Fellow of the American College of Surgeons, and Fellow of the Royal College of Ophthalmologists (United Kingdom). In 2005, Dr. Sebag was inducted into the American Ophthalmological Society, and in 2010 he was designated a Fellow of ARVO.

Explanation of optic nerve "cupping" and Cup to Disk Ration

Apr 07, 2010 - 9 comments

optic nerve cupping


cup to disk ratio

"cupping" is a term applied to the optic nerve on the back of the eye. The optic nerve generally has a "dimple" or "cup".  Ophthalmologists use a ratio called the cup to disk ration "C/D ration".  An estimate is made of the width of the cup to the width of the whole optic serve. It is usually expressed as a decimal tenth. A flat optic nerve with no cup would be C/D = .0  an optic nerve ravaged by glaucoma that is 'cupped out" would be C/D = 1.0   So the possibilies are: 0, .1,.2,.3.,.4,.5,.6,.7,.8,.9,1.0      Some physicians express two numbers one being the verticle C/D and the other being the horizontal C/D. It has been shown that these are not exact numbers. There are large variations from observer to observer and even from the same observer from visit to visit.

90% of the population without glaucoma have C/D ratios of .4 or less. So a larger C/D might indicate glaucoma. However it's very complicated. You can have glaucoma with a small C/D and not have glaucoma with a large C/D. Other factors need to be taken into account like family history of glaucoma, age, corneal thinness, intra ocular pressure (remeber you IOP varies from hour to hour just like your blood pressure and your blood sugars. Many patients with glaucoma have normal IOPs for some or even most of a 24 hour period, conversely patients without glaucoma may top out over 21 for part of the day). Another factor is if the C/D are different in each eye, usually they're the same size.

When I see a patient with a C/D ratio or .5 or more I always tell them and explain what it means so that the next ophthalmologist that examines the patient will know it's been noted before.

I would never tell a person they had "moderate cupping" without explaining what it meant and giving them "the number" to add to their medical records.  Sometimes I'll take a photograph of the optic nerves as a baseline. A new and wonderful instrument the OCT (optical coherence tomography) instrument has taken a lot of the guessing out of these issues and if there's any question at all that's the test I go to.


Timing of Cataract Surgery and High Myopia

Apr 07, 2010 - 27 comments

There is no universal time to do cataract surgery. The cardinal rule is that when the person is unable to do the things they need to do (drive at night, read, see clearly for TV, movies, perform their work) and the things they very much enjoy doing (crafts, hunting, shooting, sports, taking trips, going to friends and church at night) and the cataract is the only problem or the main problem then surgery is indicated provided the person understands the risks and the alternative of not having surgery. (In some cases there are risks to understand of NOT having surgery such as the cataract getting to hard [increases the risk of surgery], too 'ripe' [rare in the US but a big problem in so called third world countries requires emergency surgery], not being able to pass a drivers license, pilot's license, commercial driving license, increase risk of falls and disorientation in the elderly.

If there are other problems in the eye such as macular degeneration, glaucoma, diabetic retinopathy or maculopathy, amblyopia, etc. the problems will still be present after the surgery and will affect the final result. When groups of people that have had cataract surgery get together and talk about their results the variation in the final results are usually not due to complications but that those with poor vision post operatively have other problems in their eye that the cataract surgery did not, as was not expected to help.

Having said the above a commercial pilot, over the road trucker, a person that works at night, taxi drivers, etc will need cataract surgery at a relatively early stage to do their work safely and meet their job requirements. A person in their late 80's to early 90's that doesn't drive, doesn't read, rarely goes out of their house, that has multiple other physical or mental problems will likely not be bothered by a relatively large cataract and the best course of action may be to leave that 'big' cataract alone.

With your high myopia your vision was likely never a crisp 20/20 and never will be even with successful cataract surgery due to the myopic macular degeneration---something that can worsen with time. You are also at an increased risk of retinal detachment. (please see previous postings on vitreous detachment, retinal detachment, flashes/floaters/curtain & veils) on the ophthalmology website, the eyecare patient forum, use the "search feature" on the site.

Cataract surgery, even successful small incision surgery increases the risk of retinal detachment by as much as 5-10 times normal. (rough estimates 1 in 3-4 thousand for people not having had cataract surgery and no major risk factors to 1 in 500 or even less after umcomplicated surgery). Your risk without cataract surgery can be as high as 1 in 200 to 1 in 500. After cataract surgery your risk may be as high as 2-3%.

Provided you understand these risks you would be a candidate for cataract surgery anytime your feel it is a major problem as outlined above and your eye surgeon agrees.

This is what I do in my highly myopic patients that are considering or have decided to have cataract surgery.

1. I give them detailed "informed consent"
2. I sent them to a retinal specialist for a second opinion abour cataract surgery and a special detailed examination of the retinal looking for holes, tears, thin areas, vitreous traction, existing small retinal detachments. If these are present the retinal specialist will often use laser or a freezing treatment to bolster or strengthen these areas.
3. The surgery is done using several special techniques that lower the risk of surgery in the highly myopic.
4. I see the person more often than my regular patients. The myopic patient knows the symptoms of a possible retinal detachment (flashes, sudden increase of floaters, loss of peripheral vision). I instruct the patient on "finger counting visual fields" and have them check their peripheral vision at home daily.
5. At one week and 6 weeks the patient sees the retinal specialist to repeat the special examinination of the retina looking for new problems--if present they are treated.

I believe that is the information your need. If your vision is a big problem (not a small or medium size problem) and the cataract is the main reason and you have confidence in your surgeon and the surgeon agrees that surgery would be beneficial (BUT NO SURGERY IS EVERY RISK FREE) then you may want to proceed with the surgery.. (the risks are much, much less now than say 10-15 years ago due to better techniques). Because of your age (young) your will in all likelihood need cataract surgery sometime.

Good luck.