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Scanning laser polarimetry in normal subjects and patients with myopia
1Gazi University, School of Medicine, Ophthalmology Department, Ankara, Turkey.
Aims:
To examine the changes in the retinal nerve fibre layer (NFL) thickness with age and myopia in normal population.
Methods:
Retinal nerve fibre layer thickness was measured with a scanning laser polarimeter (NFA-I) in 180 normal subjects of varying age (range 7-83 years) and in 110 eyes of 85 patients with myopia of varying degrees (range -1.00 to -15.00D). They were all voluntary Anatolian people. Superior to nasal (S/N), inferior to nasal (I/N), and the superior to inferior (S/I) ratios were used for the assessment of retinal NFL thickness.
Results:
The mean superior NFL ratio was 2.96 and the mean inferior NFL ratio was 2.93 in normal subjects. There was a gradual decrease in NFL ratio with increasing age (simple regression analysis, p<0.05). The mean S/I ratio was 1.01 with a large variation. In patients with myopia, the mean superior NFL ratio was 2.60 and the mean inferior NFL ratio was 2.72. Superior and inferior NFL retardations, and S/I ratio in myopic patients were significantly (15.5%, 10.8%, and 4.9% respectively) lower than that of age matched normals (t test, p<0.05). There was also a gradual decrease in NFL thickness with increasing degree of myopia (simple regression analysis, p<0.05).
Conclusions:
Nomograms we obtained for retinal NFL thickness may serve as reference points for the assessment of normal Anatolian people and myopic patients in future studies. NFL thicknesses gradually decreased with increasing age. Patients with myopia had significantly lower NFL thicknesses than normal subjects and, although weakened by wide age range of myopic group, there is a linear relation between severity of myopia and NFL thickness in myopic patients.