Visual function changes in an animal model of retinitis pigmentosa

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Abstract

Purpose

To evaluate visual acuity and contrast sensitivity in pigmented P23H-1 rats.

Methods

The assessment of visual parameters was carried out using OptoMotry© system, CerebralMechanics Inc. Visual acuity and contrast sensitivity curve were calculated. Eight pigmented heterozygous P23H-1 rats were measured at 30, 60, 90, 120, 150, 180, 210 and 240 postnatal days. Visual function of Long Evans rats was evaluated to provide a background for the study.

Results

Age-related losses in visual acuity were found: from 0.500 cyc/deg (P30) to 0.069 cyc/deg (P240). The same trend was observed in contrast sensitivity curve. Peaks from 54.56 (P30) to 1.00 (P210 and P240) were obtained for a spatial frequency of 0.089 cycles/degree. Both parameters began to decline at 30 days of age and continued until P240, when rats were euthanized for retinal immunohistochemistry. Visual acuity of Long Evans rats was close to 0.540 cyc/deg. Contrast sensitivity curve displayed a typical inverted-U shape.

Conclusion

Visual acuity and contrast sensitivity decrease while increasing age of the P23H-1 rats. Similar results to control animals were found at P30. However, a gradual decrease in visual acuity and contrast sensitivity was observed from near normal at P30 to low levels at P240. It agrees with the progressive loss of photoreceptors.

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