Purpose: In a previous study we demonstrated that the progression of the disease retinitis pigmentosa (RP) can be readily monitored by the mean deviation (MD) measured by Humphrey central 10-2 perimetry, which assesses the sensitivity distribution in the macular area in eyes affected by RP. In the present study, we investigated whether the 10 degrees perimetric results could predict the time of declining visual acuity in eyes with RP in a cross-sectional study.
Methods: Humphrey 10-2 perimetry results and visual acuity were studied in the right eyes of 69 patients with typical RP. Patients whose eyes had cataract, glaucoma, cystoid macular edema, or other complications affecting vision were excluded.
Results: Eyes with an MD of -15 dB or greater had almost normal visual acuity. Various degrees of visual acuity loss were observed in eyes with an MD of less than -15 dB. In the 35 eyes with an MD of less than -15 dB, visual acuity correlated well with the corrected pattern standard deviation (CPSD), which is the measure of the degree to which the shape of the measured field departs from the age-corrected normal reference field.
Conclusion: In the absence of complications, many eyes with RP may experience acuity loss after the field constriction reaches an MD of less than -15 dB. The CPSD may be used as an indicator of acuity because eyes showing a lower CPSD tend to have greater loss of acuity among eyes with an equivalent MD value.