Peripheral Resolution for Achromatic and SWS Gratings in Early Glaucoma: Implications for Selective Ganglion Cell Density Loss

Abstract

Abstract: : Purpose: Measurements of achromatic grating resolution acuity in peripheral vision have been shown to be sampling limited and directly related to the underlying ganglion cell density. Recent studies have shown that peripheral grating resolution acuity for short wavelength sensitive (SWS) isolating gratings is also sampling limited and largely unaffected by lens absorption or optical defocus. Thus it permits us to make direct estimates of localized SWS-driven ganglion cell density. We wish to determine if there is any selective reduction in SWS-driven relative to achromatic ganglion cell density in early glaucoma. Methods: Resolution acuity was measured at 13° in 4 oblique meridians in 18 eyes (64.9 ± 9.4 years) with «early» glaucoma (14 POAG, 4 NTG; MD <-10dB HFA C24-2 program). The results were compared to a group of 17 age-matched normal eyes (62.5 ± 6.6 years). Results:Mean achromatic acuity was significantly lower in the glaucoma patients compared to normals (2.40 vs. 4.01 cycles/deg; P <0.01). Mean chromatic resolution was also significantly lower in the glaucoma patients than normals (0.66 vs. 0.99 cycles/deg) (P <0.01). The chromatic/achromatic resolution ratio was not statistically different in those with glaucoma compared to the normals (0.27 vs. 0.26; P =0.62) Conclusion: These initial results indicate that there is no selective reduction in SWS-driven ganglion cell density in early glaucoma.

Keywords: 415 ganglion cells • 362 color vision • 620 visual acuity