Grading nuclear cataract opacity by densitometry and objective optical analysis.

PURPOSE

To evaluate the optical quality and densitometric characteristics in eyes with early stages of crystalline lens opacification.

SETTING

Vissum-Instituto de Oftalmológico de Alicante, Alicante, Spain.

METHODS

The study included 34 eyes of 24 consecutive patients with nuclear opacity (NO) between NO1 and NO3 on the Lens Opacities Classification System III, normal corneas, and no previous ocular surgery. Intraocular aberrations were obtained by subtraction between the total and corneal optical aberrations. Modulation transfer function (MTF) was measured using a double-pass device. Lens photography and density (optical density units, Scheimpflug photography) were also evaluated. The main outcome measures were (1) spatial frequencies at 0.5 MTF and the cutoff point and (2) intraocular total and lower- and higher-order aberrations (root mean square).

RESULTS

There was an increase in lens density with the cataract grade (mean 96.7 +/- 26.0 [SD], grade NO1; 125.1 +/- 25.9, grade NO2; 167.3 +/- 40.6, grade NO3). No statistically significant differences were found in intraocular higher aberrations between groups. Significant negative correlations were found between lens density and the spatial frequency at 0.5 MTF (r = -0.400, P = .026) or the cutoff MTF (r = -0.480, P = .006).

CONCLUSIONS

The optical quality of eyes degraded with increasing cataract grade due to morphological changes such as an increase in lens density. Scheimpflug photography and MTF analysis helped objectively characterize early to moderate grades of nuclear cataract.