Cataract Epidemiology

We were pleased to see Chandrasekaran et al’s article,1Chandrasekaran S. Cumming R.G. Rochtchina E. Mitchell P. Associations between elevated intraocular pressure and glaucoma, use of glaucoma medications, and 5-year incident cataract The Blue Mountains Eye Study.Ophthalmology. 2006; 113: 417-424Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar which is generally consistent with our findings of an increased risk of nuclear opacities in persons receiving treatment to lower intraocular pressure (IOP). This result was initially reported in 2002 by the Barbados Eye Studies,2Leske M.C. Wu S.Y. Nemesure B. et al.Risk factors for incident nuclear opacities.Ophthalmology. 2002; 109: 1303-1308Abstract Full Text Full Text PDF PubMed Scopus (117) Google Scholar which Chandrasekaran et al discuss. The Barbados article concluded that “the use of topical IOP-lowering medications tripled the relative risk of nuclear opacities in this study, an association that requires verification from clinical trials.” Such confirmation was provided by the Early Manifest Glaucoma Trial (EMGT), also reported in 2002.3Heijl A. Leske M.C. Bengtsson B. et al.Reduction of intraocular pressure and glaucoma progression: results from the Early Manifest Glaucoma Trial.Arch Ophthalmol. 2002; 120: 1268-1279Crossref PubMed Scopus (2448) Google Scholar Because the EMGT publication was not referenced by Chandrasekaran et al, a brief summary of our results follows. The EMGT was a clinical trial that randomized patients with early glaucoma to treatment or no treatment. The IOP was under 21 mmHg in 52% of the EMGT patients. After a median follow-up time of 6 years, we found that patients randomized to treatment had significant increases in nuclear opacity scores with the Lens Opacities Classification System II at the slit lamp (P = 0.002) and in nuclear photograding scores (P = 0.04). These results provide further support to the presence of a link between IOP-lowering treatment and the development of nuclear opacities. Neither the Barbados study nor the EMGT found any relationship between IOP/treatment and cortical or posterior subcapsular opacities, a result similar to Chandrasekaran et al’s. We conclude that, despite methodologic differences among these 3 studies, their data jointly suggest that patients with elevated IOP or glaucoma have an increased likelihood of developing nuclear opacification, which is magnified by treatment. Such evidence thus supports Chandrasekaran et al’s conclusions.