Risk factors for second eye progression to advanced age-related macular degeneration: SST report No. 21 Submacular Surgery Trials Research Group

Ocular Neovascular Conversion and Systemic Bleeding Complications in Patients with Age-Related Macular Degeneration on Anticoagulants

PURPOSE

Conversion to neovascular disease in patients with non-neovascular age-related macular degeneration (AMD) initiated on direct oral anticoagulants (DOACs) compared with matched patients treated with warfarin.

DESIGN

Retrospective cohort study.

PARTICIPANTS

The study included 20 300 patients and 13 387 patients with non-neovascular AMD initiated on DOACs or warfarin, respectively, before propensity score matching (PSM).

METHODS

TriNetX was used to identify patients diagnosed with non-neovascular AMD stratified by treatment with DOACs or warfarin with at least 6 months of follow-up. Propensity score matching was performed to control for baseline demographics and medical comorbidities.

MAIN OUTCOME MEASURES

Relative risk (RR) of developing neovascular AMD, macular hemorrhage (MH), vitreous hemorrhage (VH), and requiring an ocular intervention (intravitreal anti-VEGF therapy or pars plana vitrectomy [PPV]) within 6 months and 1 year. Patients with chronic atrial fibrillation (AF) on anticoagulation were separately evaluated for the same measures within 5 years after initiating therapy.

RESULTS

Treatment with warfarin was associated with a higher risk of developing neovascular AMD at 6 months (RR, 1.24, 95% confidence interval [CI], 1.12-1.39; P < 0.001) and 1 year (RR, 1.26, 95% CI, 1.14-1.40; P < 0.001) when compared with matched patients treated with DOACs. There was an increased risk of requiring intravitreal anti-VEGF therapy (6 months: RR, 1.30; 95% CI, 1.13-1.49; P < 0.001; 1 year: RR, 1.31, 95% CI, 0.72-2.05; P < 0.001) and PPV (6 months: RR, 2.13; 95% CI, 1.16-3.94; P = 0.01; 1 year: RR, 2.29, 95% CI, 1.30-4.05; P = 0.003). Among patients with AMD and AF treated with warfarin, there was an increased risk of ocular complications (neovascular AMD: RR, 1.25; 95% CI, 1.14-1.38; P < 0.001; MH: RR, 1.86; 95% CI, 1.47-2.35; P < 0.001; VH: RR, 2.22; 95% CI, 1.51-3.26; P < 0.001) and need for intravitreal anti-VEGF therapy (RR, 1.34; 95% CI, 1.18-1.52; P < 0.001) over an extended 5-year period. There was no significant difference in the development of major systemic hemorrhagic events between the 2 cohorts over 5 years.

CONCLUSIONS

Patients with non-neovascular AMD treated with warfarin were more likely to develop neovascular disease and require ocular intervention for hemorrhagic complications when compared with matched patients initiated on DOACs.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Non-invasive testing for early detection of neovascular macular degeneration in unaffected second eyes of older adults: EDNA diagnostic accuracy study

BACKGROUND

Neovascular age-related macular degeneration is a leading cause of sight loss, and early detection and treatment is important. For patients with neovascular age-related macular degeneration in one eye, it is usual practice to monitor the unaffected eye. The test used to diagnose neovascular age-related macular degeneration, fundus fluorescein angiography, is an invasive test. Non-invasive tests are available, but their diagnostic accuracy is unclear.

OBJECTIVES

The primary objective was to determine the diagnostic monitoring performance of tests for neovascular age-related macular degeneration in the second eye of patients with unilateral neovascular age-related macular degeneration. The secondary objectives were the cost-effectiveness of tests and to identify predictive factors of developing neovascular age-related macular degeneration.

DESIGN

This was a multicentre, prospective, cohort, comparative diagnostic accuracy study in a monitoring setting for up to 3 years. A Cox regression risk prediction model and a Markov microsimulation model comparing cost-effectiveness of the index tests over 25 years were used.

SETTING

This took place in hospital eye services.

PARTICIPANTS

Participants were adults (aged 50-95 years) with newly diagnosed (within the previous 6 weeks) neovascular age-related macular degeneration in one eye and an unaffected second (study) eye who were attending for treatment injections in the first eye and who had a study eye baseline visual acuity of ≥ 68 Early Treatment Diabetic Retinopathy Study letters.

INTERVENTIONS

The index tests were Amsler chart (completed by participants), fundus clinical examination, optical coherence tomography, self-reported vision assessment (completed by participants) and visual acuity. The reference standard was fundus fluorescein angiography.

MAIN OUTCOME MEASURES

The main outcome measures were sensitivity and specificity; the performance of the risk predictor model; and costs and quality-adjusted life-years.

RESULTS

In total, 552 out of 578 patients who consented from 24 NHS hospitals (n = 16 ineligible; n = 10 withdrew consent) took part. The mean age of the patients was 77.4 years (standard deviation 7.7 years) and 57.2% were female. For the primary analysis, 464 patients underwent follow-up fundus fluorescein angiography and 120 developed neovascular age-related macular degeneration on fundus fluorescein angiography. The diagnostic accuracy [sensitivity (%) (95% confidence interval); specificity (%) (95% confidence interval)] was as follows: optical coherence tomography 91.7 (85.2 to 95.6); 87.8 (83.8 to 90.9)], fundus clinical examination [53.8 (44.8 to 62.5); 97.6 (95.3 to 98.9)], Amsler [33.7 (25.1 to 43.5); 81.4 (76.4 to 85.5)], visual acuity [30.0 (22.5 to 38.7); 66.3 (61.0 to 71.1)] and self-reported vision [4.2 (1.6 to 9.8); 97.0 (94.6 to 98.5)]. Optical coherence tomography had the highest sensitivity across all secondary analyses. The final prediction model for neovascular age-related macular degeneration in the non-affected eye included smoking status, family history of neovascular age-related macular degeneration, the presence of nodular drusen with or without reticular pseudodrusen, and the presence of pigmentary abnormalities [c-statistic 0.66 (95% confidence interval 0.62 to 0.71)]. Optical coherence tomography monitoring generated the greatest quality-adjusted life-years gained per patient (optical coherence tomography, 5.830; fundus clinical examination, 5.787; Amsler chart, 5.736, self-reported vision, 5.630; and visual acuity, 5.600) for the lowest health-care and social care costs (optical coherence tomography, £19,406; fundus clinical examination, £19,649; Amsler chart, £19,751; self-reported vision, £20,198; and visual acuity, £20,444) over the lifetime of the simulated cohort. Optical coherence tomography dominated the other tests or had an incremental cost-effectiveness ratio below the accepted cost-effectiveness thresholds (£20,000) across the scenarios explored.

LIMITATIONS

The diagnostic performance may be different in an unselected population without any history of neovascular age-related macular degeneration; the prediction model did not include genetic profile data, which might have improved the discriminatory performance.

CONCLUSIONS

Optical coherence tomography was the most accurate in diagnosing conversion to neovascular age-related macular degeneration in the fellow eye of patients with unilateral neovascular age-related macular degeneration. Economic modelling suggests that optical coherence tomography monitoring is cost-effective and leads to earlier diagnosis of and treatment for neovascular age-related macular degeneration in the second eye of patients being treated for neovascular age-related macular degeneration in their first eye.

FUTURE WORK

Future works should investigate the role of home monitoring, improved risk prediction models and impact on long-term visual outcomes.

STUDY REGISTRATION

This study was registered as ISRCTN48855678.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 8. See the NIHR Journals Library website for further project information.

Incidence and Progression of Nongeographic Atrophy in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT) Clinical Trial

Importance

Retinal hypopigmentation and hyperpigmentation are precursors of geographic atrophy (GA). Incidence and progression to GA in eyes treated with anti-vascular endothelial growth factor for neovascular age-related macular degeneration (nAMD) have not been investigated.

Objective

To determine the incidence and progression of non-GA (NGA) and associated risk factors.

Design, Setting, and Participants

This study is a post hoc analysis of a cohort study within the Comparison of Age-Related Treatments Trials (CATT) clinical trial. Participants were recruited February 20, 2008, through December 9, 2009; released from protocol follow-up and treatment after 2 years; and recalled from March 14, 2014, through March 31, 2015. Data analyses were conducted from January 11, 2019, through November 27, 2019.

Interventions

Participants were randomized to ranibizumab or bevacizumab for (1) 2 years of monthly or as-needed injections or (2) monthly injections for 1 year and as-needed injections the following year. Participants were treated according to best medical judgement thereafter.

Main Outcomes and Measures

Incidence of nAMD-associated NGA (hypopigmentation and hyperpigmentation in color images) and progression; adjusted risk ratios (aRR) for baseline characteristics.

Results

Among 1107 participants, risk of NGA was 35% (391 eyes), 59% (246 eyes), and 81% (122 eyes) at 1, 2, and 5 years, respectively. Risk factors for NGA included worse visual acuity (20/200-20/320: aRR, 1.74 [95% CI, 1.24-2.43], compared with ≤20/40; P = .006), larger neovascularization area (>4 disc areas: aRR, 1.31 [95% CI, 1.01-1.71], compared with ≤1 disc areas; P = .007), switched drug regimen (aRR, 1.28 [95% CI, 1.06-1.54], compared with as-needed injections; P = .02), and single-nucleotide variants Age-Related Maculopathy Susceptibility 2 (ARMS2) (TT variant: relative risk [RR], 1.53 [95% CI, 1.22-1.93]; P = .001) and HtrA Serine Peptidase 1 (HTRA1) (AG variant: RR, 1.23 [95% CI, 1.01-1.48]; AA variant: RR, 1.51 [95% CI, 1.20-1.91]; P = .002). Sub-retinal pigment epithelium thickness was protective (>275 μm: aRR, 0.59 [95% CI, 0.46-0.75], compared with ≤75 μm; P < .001). Among 389 eyes with NGA by 2 years and subsequent color images, risk of progression to GA was 29%, 43%, and 50% at 1, 3, and 4 years, respectively. Risk factors for progression to GA included worse visual acuity (20/200-20/320: aRR, 2.75 [95% CI, 1.54-4.93], compared with ≤20/40; P < .001), worse fellow-eye visual acuity (<20/40: aRR, 1.77 [95% CI, 1.12-2.79], compared with ≥20/40; P = .01), fellow-eye GA (aRR, 1.71 [95% CI, 1.06-2.75]; P = .03), and pseudodrusen in either eye (aRR, 1.65 [95% CI, 1.17-2.34]; P = .005). Subretinal fluid was associated with a decreased risk of progression (aRR, 0.42 [95% CI, 0.28-0.63]; P < .001).

Conclusions and Relevance

In this study, after 2 years of protocol-guided anti-vascular endothelial growth factor treatment for nAMD, more than half of the eyes in the study developed NGA in the location of nAMD. After 3 additional years of regular care, half of them progressed to GA.

Trial Registration

ClinicalTrials.gov Identifier: NCT00593450.

Efficacy and Safety of Lampalizumab for Geographic Atrophy Due to Age-Related Macular Degeneration: Chroma and Spectri Phase 3 Randomized Clinical Trials

Importance

Geographic atrophy (GA) secondary to age-related macular degeneration is a leading cause of visual disability in older individuals. A phase 2 trial suggested that lampalizumab, a selective complement factor D inhibitor, reduced the rate of GA enlargement, warranting phase 3 trials.

Objective

To assess the safety and efficacy of lampalizumab vs sham procedure on enlargement of GA.

Design, Setting, and Participants

Two identically designed phase 3 double-masked, randomized, sham-controlled clinical trials, Chroma and Spectri, enrolled participants from August 28, 2014, to October 6, 2016, at 275 sites in 23 countries. Participants were aged 50 years or older, with bilateral GA and no prior or active choroidal neovascularization in either eye and GA lesions in the study eye measuring 2.54 to 17.78 mm2 with diffuse or banded fundus autofluorescence patterns.

Interventions

Participants were randomized 2:1:2:1 to receive 10 mg of intravitreous lampalizumab every 4 weeks, sham procedure every 4 weeks, 10 mg of lampalizumab every 6 weeks, or sham procedure every 6 weeks, through 96 weeks.

Main Outcomes and Measures

Safety and efficacy assessed as mean change from baseline in GA lesion area at week 48 from centrally read fundus autofluorescence images of the lampalizumab arms vs pooled sham arms, in the intent-to-treat population and by complement factor I-profile genetic biomarker.

Results

A total of 906 participants (553 women and 353 men; mean [SD] age, 78.1 [8.1] years) were enrolled in Chroma and 975 participants (578 women and 397 men; mean [SD] age, 77.9 [8.1] years) were enrolled in Spectri; 1733 of the 1881 participants (92.1%) completed the studies through 48 weeks. The adjusted mean increases in GA lesion area from baseline at week 48 were 1.93 to 2.09 mm2 across all groups in both studies. Differences in adjusted mean change in GA lesion area (lampalizumab minus sham) were -0.02 mm2 (95% CI, -0.21 to 0.16 mm2; P = .80) for lampalizumab every 4 weeks in Chroma, 0.16 mm2 (95% CI, 0.00-0.31 mm2; P = .048) for lampalizumab every 4 weeks in Spectri, 0.05 mm2 (95% CI, -0.13 to 0.24 mm2; P = .59) for lampalizumab every 6 weeks in Chroma, and 0.09 mm2 (95% CI, -0.07 to 0.24 mm2; P = .27) for lampalizumab every 6 weeks in Spectri. No benefit of lampalizumab was observed across prespecified subgroups, including by complement factor I-profile biomarker. Endophthalmitis occurred after 5 of 12 447 injections (0.04%) or in 5 of 1252 treated participants (0.4%) through week 48.

Conclusions and Relevance

In Chroma and Spectri, the largest studies of GA conducted to date, lampalizumab did not reduce GA enlargement vs sham during 48 weeks of treatment. Results highlight the substantial and consistent enlargement of GA, at a mean of approximately 2 mm2 per year.

Trial Registration

ClinicalTrials.gov Identifier: NCT02247479 and NCT02247531.

Imaging, Genetic, and Demographic Factors Associated With Conversion to Neovascular Age-Related Macular Degeneration: Secondary Analysis of a Randomized Clinical Trial

Importance

Risk factors associated with the development of neovascular age-related macular degeneration (AMD) have been identified. However, population size and methods to integrate imaging, genetic, and demographic factors associated with conversion to neovascular AMD are limited, specifically when treatment is administered in 1 eye.

Objective

To determine the imaging, genetic, and demographic factors associated with conversion from nonneovascular to neovascular AMD in fellow eyes.

Design, Setting, and Participants

This post hoc secondary analysis of the 24-month phase 3 multicenter, double-masked, active treatment-controlled HARBOR trial included 686 fellow eyes with nonneovascular AMD at baseline. Imaging features describing the presence, number, extent, density, and relative reflectivity of drusen were automatically extracted from spectral-domain optical coherence tomography scans. Genetic analysis included 34 single-nucleotide polymorphisms. Least absolute shrinkage and selection operator regression was performed to narrow imaging features. Survival analysis and Cox proportional hazards regression were performed to determine the association of the selected imaging features and genetic and demographic factors with conversion to neovascular AMD. Data were collected from November 2016 through October 2017 and analyzed from October 2017 through October 2018.

Exposure

Nonneovascular AMD in the fellow eye.

Main Outcomes and Measures

Features associated with conversion to neovascular AMD. Hazard ratios (HRs) and their 95% CIs were calculated.

Results

Among the 686 fellow eyes included in the analysis (406 [59.2%] women; mean [SD] age, 78.12 [8.28] years), 154 (22.4%) converted to neovascular AMD. Female sex was significantly associated with conversion to neovascular AMD (HR, 1.57; 95% CI, 1.11-2.20; P = .009). After controlling for demographic and treatment effects, drusen area within 3 mm of the fovea (HR, 1.45; 95% CI, 1.24-1.69; HR for 1-SD increase, 1.36 [95% CI, 1.20-1.54]) and mean drusen reflectivity (HR, 3.97; 95% CI, 1.11-14.18; HR for 1-SD increase, 1.32 [95% CI, 1.02-1.71]) were significantly associated with conversion to neovascular AMD. In addition, 1 genetic variant (rs61941274) was found to be associated with conversion to neovascular AMD.

Conclusions and Relevance

Two imaging features (total en face area of drusen restricted to a circular area 3 mm from the fovea and mean drusen reflectivity) and 1 genetic variant (ACAD10 locus) were associated with conversion to neovascular AMD. Drusen characteristics may be associated with conversion to neovascular AMD despite treatment in 1 eye.

Trial Registration

ClinicalTrials.gov identifier: NCT00891735.

Low incidence of choroidal neovascularization following subthreshold diode micropulse laser (SDM) in high-risk AMD

Purpose

To determine the incidence of new choroidal neovascularization (CNV) in eyes with dry age-related macular degeneration (AMD) following subthreshold diode micropulse laser (SDM).

Method

In an observational retrospective cohort study, the records of all patients active in the electronic medical records database were reviewed to identify eyes with dry AMD treated with SDM. Identified eyes were classified by simplified AREDS categories, and analyzed for the primary endpoint of new CNV after treatment.

Results

The EMR revealed SDM was offered to 373/392 (95%) patients with dry AMD and elected by 363/373 (97%) between 2008–2017. Follow up was available for 354/363 patients (547 eyes, 98%) (range 6–108 mos., avg. 22). CNV risk factors included age (median 84 years, 67% > 80); reticular pseudodrusen (214 eyes, 39%); AREDS category (78% category 3 and 4); and fellow eye CNV (128 eyes, 23%). New CNV developed in 9/547 eyes (1.6%, annualized rate 0.87%). Visual acuity was unchanged. There were no adverse treatment effects.

Summary

In a review of a large group of eyes with exceptionally high-risk AMD, SDM was followed by a very low incidence of new CNV. If confirmed by further study, SDM would offer a new and highly effective treatment to reduce the risk of vision loss from AMD.

Incidence and risk factors for neovascular age-related macular degeneration in the fellow eye

PURPOSE

The epidemiology, risk factors, and the effect of anti-VEGF treatment on neovascular age-related macular degeneration (nAMD) have primarily been studied in the first eye developing the disease. The understanding of pathophysiology and planning of follow-up examinations can be improved by knowledge of incidence and risk factors for development of the disease in the fellow eye.

METHODS

In a prospective observational cohort study, epidemiological and clinical risk factors for the development of nAMD in the fellow eye among 2516 patients consecutively diagnosed with the disease from a population of 0.9 million citizens during a period of more than 10 years were studied.

RESULTS

nAMD had been diagnosed in the fellow eye of 541 (21.5%) of the patients. The incidence of fellow-eye involvement increased from approximately 5% in patients initially presenting with bilateral disease to approximately 28% more than 6 years after the diagnosis in the first eye. Visual acuity (VA) was higher and central retinal thickness (CRT) was lower in fellow eyes with nAMD diagnosed later than the first eye. Male gender, increasing leakage area, and peripapillary location of the subretinal neovascular membrane in the first eye reduced the risk of developing disease in the fellow eye.

CONCLUSIONS

The planning of follow-up examinations of patients diagnosed with nAMD in one eye should consider that the risk of fellow-eye involvement is higher within the first 6 years, in women, and when the leakage area in the first eye is small and not located peripapillary.

Visual outcomes in relation to time to treatment in neovascular age-related macular degeneration

PURPOSE

To study the relation between the interval from diagnosis to initiation of intravitreal injection therapy and visual outcome in neovascular age-related macular degeneration (nAMD) and to report changes over time in fellow-eye status.

METHODS

Retrospective chart review. The study included 1185 eyes in 1099 patients who began vascular endothelial growth factor inhibitor treatment for nAMD during four separate periods in 2007, 2009, 2011 and 2012 using a fixed loading-dose regimen of three ranibizumab injections.

RESULTS

Mean best-corrected visual acuity (BCVA) at presentation remained within the range 0.23-0.24 Snellen and the median patient age within 79-80 years, whereas BCVA at first visit after the third injection increased from 0.24 to 0.31 (p < 0.0001) in concert with a shift in preferred practice from separate-day injection to same-day injection. This led to a reduction in the median time to treatment from 16 days to 1 day. The proportion of patients with fellow-eye BCVA 0.05 or worse at presentation with newly diagnosed wet AMD in the incident eye decreased from 38% to 22% (p < 0.0018). The proportion of bilaterally treated patients increased during the study period.

CONCLUSION

In this study, 2-week-earlier injection was associated with the equivalent of a 5-Early Treatment Diabetic Retinopathy Study letter-gain in mean visual acuity at 3 months after presentation. The difference is larger than expected from the 2-week-longer duration of disease at the study end-point. The study supports that early diagnosis and treatment of nAMD is of value for functional outcomes.

Geographic atrophy: a histopathological assessment

IMPORTANCE

Geographic atrophy (GA) is the major cause of blind registration in Western communities, although, with few exceptions, it is less common than choroidal neovascular disease. The variation of phenotype implies that age-related macular degeneration (AMD) does not follow the same course from one case to another and that phenotyping may be important before initiating a therapeutic trial.

OBJECTIVE

To document photoreceptor and retinal pigment epithelium (RPE) cell loss and other changes at the RPE-choroid interface in donated human eyes in which visual loss was deemed to be due to GA.

DESIGN, SETTING, AND PARTICIPANTS

Histological study of a consecutive series of eyes donated by individuals previously diagnosed clinically as having GA. Donors were chosen on the basis of available clinical records (from MidAmerica Transplant Services, St Louis, Missouri; the Iowa Lions Eye Bank, Iowa City; and the Utah Lions Eye Bank, Salt Lake City) and selected were those considered to have GA due to AMD. Tissues in the regions of atrophy were examined with light, electron, and autofluorescence microscopy.

RESULTS

In most of the 37 donors examined, there was marked loss of photoreceptor cells for variable distances distal from the edge of the GA. Rod loss was greater than cone loss. An inverse relationship existed between the quantity of autofluorescent inclusions in the RPE and the thickness of sub-RPE basal laminar deposit. Integrity of the choroid varied from one eye to another and was not related strictly to photoreceptor survival. In some eyes, photoreceptor loss existed in the absence of obvious morphological changes in the Bruch membrane or RPE.

CONCLUSIONS AND RELEVANCE

The findings support the view that photoreceptor loss occurs early in AMD in a proportion of cases and imply that photoreceptor-cell loss may contribute to the functional loss recorded in early stages of AMD at least in part. The variation of changes from one eye to another implies that patients selected for a specific prophylactic therapy for early AMD should be chosen on the basis of the characteristics of their disease.

Comparison of macular pigment in patients with age-related macular degeneration and healthy control subjects - a study using spectral fundus reflectance

PURPOSE

Previous studies have reported an age-dependent decline of macular pigment optical density (MPOD) as well as a relative lack of MPOD in age-related macular degeneration (AMD). Results are, however, strongly dependent on the technique used. In this study, we investigated the age dependence of MPOD using spectral fundus reflectance. In addition, we hypothesized that patients with AMD have a reduced MPOD as compared to healthy controls.

METHODS

A total of 85 healthy subjects and 96 patients with AMD were included in this study. The healthy control subjects showed a wide range of ages (mean, 51.6 years; range, 21-79years). Patients with AMD were significantly older (mean, 71.2 years; range, 50-89 years). Spectral fundus reflectance of the fovea was measured in a 2.3° detection field with a custom built fundus reflectometer. Calculation of MPOD was based on a previously published fundus reflectance model.

RESULTS

Patients with AMD showed a reduced MPOD (0.35 ± 0.12) as compared to the healthy control group (0.39 ± 0.12, p = 0.013 between groups). No age dependence of MPOD (r = -0.14, p = 0.19) was found in the healthy control group. In the AMD group, however, MPOD declined with age (r = -0.24, p = 0.019).

CONCLUSIONS

This study indicates that MPOD is reduced in patients with AMD. In addition, the data of this study indicate that MPOD is age dependent in AMD patients, but not in healthy controls. Taken together with data indicating that lutein supplementation increases MPOD, this provides a rationale for supplementation of the macular pigments in patients with AMD, although long-term clinical outcome data are lacking.

Short- and mid-term repeatability of macular pigment optical density measurements using spectral fundus reflectance

BACKGROUND

Several methods have been proposed for measuring macular pigment optical density (MPOD). To date, none of the realized techniques can be considered as "gold standard". A key issue for the clinical applicability of a method is its repeatability. In this study, we investigated short- and mid-term repeatability of MPOD measurements using reflectometry.

METHODS

A total of 12 healthy young subjects were measured 5 times on 5 consecutive days. Repeatability over 6 months was investigated in patients with AMD. The data in AMD patients were taken from a recently published placebo controlled study investigating the effect of lutein supplementation on MPOD (n = 37; [1]). Four measurements over 6 months were used to calculate repeatability. Spectral fundus reflectance of the fovea was measured in a 2.3° detection field with a custom-built fundus reflectometer. Calculation of MPOD was based on a previously published fundus reflectance model.

RESULTS

The coefficients of variation were 6.2 ± 2.4% and 8.0 ± 5.5% in the healthy and AMD group, respectively. Bland-Altman plots indicate that the difference between measurements at day 1 and day 5 in healthy subjects and day 1 and month 6 in AMD patients was small. The maximum deviation in MPOD in a healthy subject was 0.07 (22.6%), and 0.17 (51.5%) in a patient with AMD.

CONCLUSIONS

Reflectometry provides adequate short-term and mid-term repeatability for measuring MPOD. Accordingly, the technique makes it possible to monitor MPOD in patients with AMD and to study the influence of supplementation in these subjects. In addition, the variability of the technique is small enough to allow for clinical trials with reasonable sample size.

Optical coherence tomography changes before the development of choroidal neovascularization in second eyes of patients with bilateral wet macular degeneration

AIM

To describe the frequency of neovascular age-related macular degeneration (nAMD) in second eyes of patients undergoing ranibizumab therapy in their first eye and to evaluate the patterns of optical coherence tomography (OCT) abnormalities in fellow eyes before nAMD.

METHOD

Patients who developed choroidal neovascularization (CNV) in the second eye while on treatment for the first eye were identified. OCT scans of the second eyes, performed before the onset of CNV, were retrospectively examined and graded. Frequency of second eye involvement was estimated and patterns of progression of OCT abnormalities were described and classified.

RESULTS

In all, 65 out of 749 consecutive patients required ranibizumab in their second eye for treatment-naïve nAMD over a 2-year period. The mean interval from commencement of ranibizumab in first eye to conversion in second eye was 12 months (2-35.5 months). There were three patterns of CNV development: group A (12%, n=8) had no OCT abnormalities in the second eye just before developing CNV; group B (38%, n=25) had no abnormalities at baseline but developed OCT changes more than one visit before conversion and group C (50%, n=32) had OCT changes from baseline, which did not progress until just before conversion.

CONCLUSION

Patients with retinal pigment epithelial elevation without sub-retinal fluid on OCT in their fellow eyes have a high risk of progression to require therapy within a 2-year period. An anticipatory approach may be warranted, but a small group with completely normal OCT appearances can still develop lesions between visits.

Metabolic physiology in age related macular degeneration

Ischemia and hypoxia have been implicated in the pathophysiology of age related macular degeneration (AMD). This has mostly been based on studies on choroidal perfusion, which is not the only contributor to retinal hypoxia found in AMD eyes. Other features of AMD may also interfere with retinal oxygen metabolism including confluent drusen, serous or hemorrhagic retinal detachment, retinal edema and vitreoretinal adhesion. Each of these features contributes to retinal hypoxia: the drusen and retinal elevation by increasing the distance between the choriocapillaris and retina; vitreoretinal adhesion by reducing diffusion and convection of oxygen towards and vascular endothelial growth factor (VEGF) away from hypoxic retinal areas. Hypoxia-inducible-factor is known to exist in subretinal neovascularization and hypoxia is the main stimulus for the production of VEGF. Each feature may not by itself create enough hypoxia and VEGF accumulation to stimulate wet AMD, but they may combine to do so. Choroidal ischemia in AMD has been demonstrated by many researchers, using different technologies. Choroidal ischemia obviously decreases oxygen delivery to the outer retina. Confluent drusen, thickening of Bruch's membrane and any detachment of retina or retinal pigment epithelium, increases the distance between the choriocapillaris and the retina and thereby reduces the oxygen flux from the choroid to the outer retina according to Fick's law of diffusion. Retinal elevation and choroidal ischemia may combine forces to reduce choroidal oxygen delivery to the outer retina, produce retinal hypoxia. Hypoxia leads to production of VEGF leading to neovascularization and tissue edema. A vicious cycle may develop, where VEGF production increases effusion, retinal detachment and edema, further increasing hypoxia and VEGF production. Adhesion of the viscous posterior vitreous cortex to the retina maintains a barrier to diffusion and convection currents in the vitreous cavity according to the laws of Fick's, Stokes-Einstein and Hagen-Poiseuille. If the vitreous is detached from the surface of the retina, the low viscosity fluid transports oxygen and nutrients towards an ischemic area of the retina, and cytokines away from the retina, at a faster rate than through attached vitreous gel. Vitreoretinal adhesion can exacerbate retinal hypoxia and accumulation of cytokines, such as VEGF. Vitreoretinal traction can also cause hypoxia by retinal elevation. Conceivably, the basic features of AMD, drusen, choroidal ischemia, and vitreoretinal adhesion are independently determined by genetics and environment and may combine in variable proportions. If the resulting hypoxia and consequent VEGF accumulation crosses a threshold, this will trigger effusion and neovascularization.