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S. Bozbeyoglu, G.A. Fishman, R.W. Massof; Natural Course of Visual Field Loss in Patients With Usher Syndrome Type 2 . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1064.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the natural course of visual field loss in patients with type 2 Usher syndrome and different patterns of visual field loss.
Fifty–eight patients with type 2 Usher syndrome who had at least 3 visual field measurements during a period of at least 3 years were studied.The mean ages of the 58 patients at their initial and most recent visits were 29.4±2.2 and 41.7±1.6 years, respectively. Kinetic visual fields measured on a standard calibrated Goldmann perimeter were analyzed.The visual field areas in both eyes were determined by planimetry with the use of a digitalizing tablet and computer software and expressed in square inches. The data for each visual field area measurement were transformed to a natural log unit. After regression lines were obtained, values for the half–life of field loss were computed.Three different patterns of visual field loss were identified, and the half–life time for each pattern loss was calculated. These patterns included the following: Type I: Concentric loss. Type II: Progressive loss from superior to inferior retina that progressed in an arcuate fashion from nasal to temporal or temporal to nasal, eventually leaving peripheral and/or central remnants. Type III: Complete or partial ring scotomas. The remaining fields (N=21) were defined as unclassified since no specific identifiable pattern could be observed.
Of the 58 patients, 11 were classified as having pattern Type I, 12 with pattern Type II and 14 with pattern Type III. For the V4e target, the average half–life times among the different patterns of field loss, considering both eyes, varied from 5.9 to 6.6, 5.0 to 5.4 and 6.9 to 7.0 years in Type I, Type II and Type III patterns, respectively. For target II4e, the average half–life times varied from 4.8 to 5.0, 5.8 to 6.2 and 3.8 to 4.0 years in Type I, II and III patterns, respectively. Of the 21 patients whose visual field loss was so advanced that they could not be classified, 15 showed only a small residual central field (Group A) and 6 showed a residual central field with a peripheral temporal island (Group B). In this group, average half–life time values for field loss varied from 4.3 to 6.3 years for the V4e target and 3.6 to 6.4 years for the II4e target. There was no significant difference in the half–life times between the various groups for the two isopters or between right and left eyes.
The half–life times for visual field loss in patients with Usher syndrome type 2 were independent of the pattern of visual field loss. The data obtained on our cohort of these patients are of value for counseling patients as to their visual prognosis.
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