Straylight and Visual Quality on Early Nuclear and Posterior Subcapsular Cataracts

ABSTRACT

Purpose: To measure log(s) and OSI parameters, both related to forward light scattering in the eye, in subjects with different kinds of early cataracts—nuclear or posterior subcapsular—and corrected visual acuity (CVA).

Methods: 34 eyes of 19 patients ranged between 50 and 75 years old with diagnosed nuclear (14 eyes) or posterior subcapsular cataract (20 eyes) were recruited. Only NO1, NO2, P1, and P2 opacity scores according to LOCS III were included. Observer examination included visual acuity, contrast threshold (Ct), and measurements performed by straylightmeter (straylight parameter log(s)) and double-pass instrument (objective scatter index (OSI)).

Results: OSI and log(s) were correlated with LOCSIII in nuclear opacities (p = 0.015 and 0.004, respectively) and in the whole data (p = 0.027 and 0.019, respectively) but did not for posterior subcapsular opacities alone. OSI was strongly correlated with log(s) in nuclear (r = 0.885 and p < 0.001) but not in posterior subcapsular cases (r = 0.382 and p = 0.097). Ct was correlated with log(s) for both cataract types (p = 0.043 for nuclear and p= 0.005 for posterior subcapsular cataract) but not with OSI (p = 0.093 for nuclear and p = 0.064 for posterior subcapsular cataract).

Conclusions: OSI and log(s) discriminate early stages of nuclear cataracts when taking LOCS III as reference, so these opacities could be graded by any of those parameters. LOCSIII does not represent the visual condition for posterior subcapsular cataract. Straylightmeter measurements express the loss in contrast sensitivity caused by nuclear and posterior subcapsular opacities. Studies of lens opacities must be separated according to the type of opacity present in eyes.

KEYWORDS:

• Contrast threshold
• nuclear cataract
• posterior subcapsular cataract
• straylight
• visual quality

Acknowledgments

The authors wish to acknowledge to Cátedra de Oftalmología of the Universidad Nacional de Tucumán and Instituto de Microcirugía Oftalmológica for their collaboration in the selection and clinical evaluation stage.

Funding

This research was supported by Consejo de Investigación de la Universidad Nacional de Tucumán under Grant CIUNT 26/E519, Agencia Nacional Argentina de Promoción de la Ciencia y Tecnología under Grant ANPCyT PICT 2011 Nº1807, and Consejo Nacional de Investigaciones Científicas y Técnicas under Grant CONICET PIP 0553.

Declaration of interests

Issolio and Colombo have a licensed patent and a pending patent regarding contrast sensitivity measurement system FVC-100 used in this work. Paz Filgueira and Sánchez have no conflict of interest with the companies of instruments used in this study. The authors alone are responsible for the content and writing of the article.

Additional information

Funding

This research was supported by Consejo de Investigación de la Universidad Nacional de Tucumán under Grant CIUNT 26/E519, Agencia Nacional Argentina de Promoción de la Ciencia y Tecnología under Grant ANPCyT PICT 2011 Nº1807, and Consejo Nacional de Investigaciones Científicas y Técnicas under Grant CONICET PIP 0553.