Why is glaucoma associated with exfoliation syndrome

Aim: To investigate the correlation between retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) size in normal white subjects by means of optical coherence tomography (OCT).

Methods: 54 eyes of 54 healthy subjects aged between 15 and 54 underwent peripapillary RNFL thickness measurement by a series of three circular scans with a 3.4 mm diameter (Stratus OCT, RNFL Thickness 3.4 acquisition protocol). ONH analysis was performed by means of six radial scans centred on the optic disc (Stratus OCT, Fast Optic Disc acquisition protocol). The mean RNFL values were correlated with the data obtained by ONH analysis.

Results: The superior, nasal, and inferior quadrant RNFL thickness showed a significant correlation with the optic disc area (R = 0.3822, p = 0.0043), (R = 0.3024, p = 0.026), (R = 0.4048, p =  0.0024) and the horizontal disc diameter (R = 0.2971, p = 0.0291), (R = 0.2752, p = 0.044), (R = 0.3970, p = 0.003). The superior and inferior quadrant RNFL thickness was also positively correlated with the vertical disc diameter (R = 0.3774, p = 0.0049), (R = 0.2793, p = 0.0408). A significant correlation was observed between the 360° average RNFL thickness and the optic disc area and the vertical and horizontal disc diameters of the ONH (R = 0.4985, p = 0.0001), (R = 0.4454, p = 0.0007), (R = 0.4301, p = 0.0012).

Conclusions: RNFL thickness measurements obtained by Stratus OCT increased significantly with an increase in optic disc size. It is not clear if eyes with large ONHs show a thicker RNFL as a result of an increased amount of nerve fibres or to the shorter distance between the circular scan and the optic disc edge.

https://bjo.bmj.com/content/bjophthalmol/89/4/489.full.pdf

Correlation between retinal nerve fibre layer thickness and optic nerve head size: an optical coherence tomography study

This introductory lecture to the epidemiological session in the Workshop on the Exfoliation Syndrome (ES) gathers together figures for the prevalence of ES around the world. Prevalence figures from published reports are shown in the text separately for each country. Four ways of comparing the prevalences are used. 1) Prevalences in people over 60 years of age, 2) Percentages of glaucoma in persons with ES, 3) Percentages of ES in patients with glaucoma or ocular hypertension, with separate statistics for the proportion of capsular glaucoma in patients treated with laser trabeculoplasty (LTP), 4) Prevalence of ES in patients with cataract. The major differences in prevalence can partly be explained by the different techniques used in the investigations. Very few authors have studied people in different countries, which is the best way of obtaining comparable results. The author has personally studied Finns, Lapps, Eskimos in Greenland, Canada and Alaska, Icelanders, populations in Tunis, India and Peru and four populations in the USSR by the same technique. The prevalences vary from 0% in Eskimos to 21% in Finns over 60 years of age, and are at the same high level in Lapps, Finns, Russians in Novosibirsk and Icelanders, but significantly lower in all the others. The results support the opinion that ES is not uniformly distributed in all countries, and this is confirmed by many reports from different countries in this workshop.

Exfoliation syndrome in various ethnic populations.

Long-term Follow-up of Pseudoexfoliation and the Development of Elevated Intraocular Pressure

BACKGROUNDThe Q-switched alexandrite laser (755 nm, 100 nanoseconds) selectively targets and destroys cutaneous pigment such as that found in dermal pigmented lesions and tattoos. The nevus of Ota is a benign dermal melanocytic lesion, which, due to its large size and periocular location, has been n

Treatment of nevus of Ota by the Q-switched alexandrite laser

The retinal function of patients with high refractive error was studied electroretinographically. Thirty-one hypermetropic patients, 7 myopic patients, and 7 patients with either unilateral or bilateral aphakia participated in the study. The ERG responses were measured in the light- and dark-adapted states. It was found that myopic eyes were characterised by subnormal amplitude but normal pattern, expressed by normal relationship between the b-wave amplitude and the a-wave amplitude. In aphakia the ERG responses were of normal amplitude and pattern. However, the hypermetropic patients could be divided into 3 groups. One group included subjects with a subnormal b-wave to a-wave relationship. The second group was characterised by a normal b- to a-wave relationship, while patients belonging to the third group exhibited supernormal b-wave to a-wave relationship. This classification of hypermetropic subjects did not correlate with the axial length of the eye or the refraction of the ocular media.

https://bjo.bmj.com/content/bjophthalmol/68/2/79.full.pdf

Retinal function in high refractive error assessed electroretinographically.

Night vision was tested electroretinographically and psychophysically in a vitamin A deficient patient before and after therapy. Vitamin A deficiency resulted from malabsorption due to a jeujunoileal bypass operation. Before therapy the patient had severely reduced cone and rod function. After the reversal operation, accompanied by 5 injections of a total of 500,000 units of vitamin A, complete recovery of cone and rod functions was observed within 7 months. Shortly after therapy rod sensitivity reached the normal level, while the time course of rod adaptation remained slower than normal and the dark-adapted electroretinographic (ERG) responses were subnormal. At later stages the ERG responses reached normal amplitudes but rod adaptation stayed slow. Only after 7 months did night vision reach the normal level with regard to the time course of rod adaptation, rod sensitivity, and ERG responses.

https://bjo.bmj.com/content/bjophthalmol/67/1/37.full.pdf

Night vision in a case of vitamin A deficiency due to malabsorption.

The prevalence of pseudoexfoliation among patients of Sephardic origin was more than twice the expected when compared with the ethnic distribution of the population consulting the Rambam Medical Center eye clinic. A strong association between brown irises and pseudoexfoliation was noted. No uniform scanning electron microscope pattern was seen of the pseudoexfoliation.

T. Haim

Papers

Retinal function in high refractive error assessed electroretinographically.

Night vision in a case of vitamin A deficiency due to malabsorption.

Pseudoexfoliation: epidemiology, clinical and scanning electron microscopic study.

Oculodermal melanocytosis (nevus of Ota) and orbital malignant melanoma.