Functional aspects of drusen regression in age-related macular degeneration.

AIMS: To investigate the functional implications of macular soft drusen regression in AMD eyes. METHODS: Patients were selected from a large ongoing collection of clinical data at Moorfields Eye Hospital. Phenotyping based on standard colour fundus images was performed according to the system defined by the International Classification for ARM, by certified graders masked to the main aim of the study. Fundus autofluorescence (FA) was recorded using a Heidelberg Retina Angiograph 2. Where drusen regression was confirmed by independent grading, the patient was invited for photopic and scotopic fine matrix mapping (FMM). Phenotype and functional data were analysed for correlations between fundus appearance, autofluorescence and retinal sensitivity. RESULTS: Fundus and FA images of 960 patients were screened, soft drusen regression was detected in 34 cases, and 14 patients agreed to participate in the study, ranging in age from 52 to 84 years (median 72). The mean follow-up period was 5.9 years (range 2.8-14.4 years). FMM showed generalised threshold elevation relative to normal controls both under photopic and scotopic conditions. Scotopic sensitivity loss exceeded photopic loss in all cases. Sensitivity loss over areas with drusen or regressed drusen did not differ significantly from that over non-drusen areas. CONCLUSION: Macular soft drusen may fade or disappear without detectable ophthalmoscopic, FA or psychophysical signs of local dysfunction. This phenomenon is a potential source of misclassification. The prognosis for cases with true regression of drusen compared with those without needs to be considered in future studies on AMD.

Vital staining with indocyanine green: a review of the clinical and experimental studies relating to safety.

Indocyanine green (ICG) is extremely effective when used as a vital stain during macular hole surgery. By staining the internal limiting membrane, ICG facilitates removal of this delicate and sometimes hard to visualize structure. There is, however, considerable debate regarding its safety. This review considers the clinical and experimental studies of ICG and a related agent, infracyanine green. Some clinical papers show visual field defects, reduced visual acuity, and persistence of ICG at the macula and optic nerve. Other clinical studies fail to demonstrate toxicity. The experimental studies are also conflicting, but there are emerging trends. These suggest that surgeons who continue to use ICG should use concentrations not greater than 0.05 mg/ml, in fluid-filled eyes, with short exposure times, iso-osmolar solutions, and avoid proximal or prolonged endoillumination of stained tissue. A smaller number of studies suggest that infracyanine green produces similar staining to ICG, and may possibly be safer, but there are too few well-designed studies to reach a conclusion. Although the use of ICG continues, on the balance of evidence, this review suggests that it is has the potential to produce subtle visual damage.