Lens and Cataract Landmark Studies

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Time to eat your veggies to prevent cataracts!  In the 1991 LOCS study, risk factors were determined for the development of nuclear, cortical, posterior subcapsular, and mixed cataracts using 1380 patients with known cataracts. There were 435 controls alongside 72 posterior subcapsular, 137 nuclear, 290 cortical, and 446 mixed cataracts.  

Key Points:

• Cataracts are related to low socioeconomic and nutritional status
• Diabetes is a risk factor for all types of cataracts except for nuclear
• Oral steroid use increased risk for posterior subcapsular cataracts
• Risk factors for cortical cataracts: nonwhite race and female sex
• Risk factors for mixed cataracts: gout medications, family history, and myopia 

Overall, the LOCS study is a landmark study because it determined the various personal, nutritional, medical, and other exposures that lead to cataract formation, which are now part of numerous clinical discussions around the development of cataracts.

Older, wiser, and a little blurrier – must be those cataracts! Cataracts are an incredibly common cause of decreased vision across the world, especially among older individuals. Researchers in Beaver Dam Eye Study set out to gather longitudinal data to better investigate characteristics associated with cataract development in order to shed light on areas of greater social and health care needs. This prospective epidemiologic study utilized census data of 2764 participants living in a rural town in the midwestern United States in order to determine the incidence of age-related cataracts and cataract surgery over a 10-year period. Lenses of participants were photographed and graded according to standardized protocol at baseline, 5 years, and 10 years.

Key Points:

• In both men and women, the 10-year incidence of both cataract (nuclear, cortical, and/or posterior subcapsular) and cataract surgery increased with age
• The greatest increase in incidence for nuclear sclerotic cataract was seen in those 55 to 64 years old (at baseline).
• Compared to men, women were found to be at increased risk of both nuclear sclerotic cataracts and cataract surgery (P< 0.0001). 

The Beaver Dam Eye Study is a critical piece of literature in the epidemiology of cataract development as it provided long-term data to better appreciate the role of age and gender in cataract progression. Its contributions to the early understanding of the incidence and prevalence of different lens opacities make it landmark study in ophthalmology.

Is more always better? Or, more money, more problems? In this study from 2000, preoperative medical testing was compared to no preoperative medical testing prior to age-related cataract surgery in 19,250 total cataract surgeries. They randomized patients to a no testing and a routine testing group, and assessed for medical adverse events during and within 7 days of the surgery.

Key Points:  

• Routine preoperative medical testing did not reduce the risk of adverse events during or after age-related cataract surgery (cumulative events were 31.3 per 1000 for both groups)
• Secondary analysis showed no specific benefit when segmenting for age, sex, race, or health status

Overall, the study is a landmark study because it showed that preoperative medical testing before age-related cataract surgery does not provide any significant benefit or improve postoperative outcomes. Further studies and reviews have instead showed that it primarily increases medical costs for patients with age-related cataracts.

If an apple-a-day keeps the doctor away, what keeps away endophthalmitis? While endophthalmitis is rare, invasion of the globe during cataract surgery is a risk factor and must be taken into consideration before, during, and after the procedure. In an effort to better understand ways to prevent such a postoperative complication, the ESCRS (European Society of Cataract and Refractive Surgeons) endophthalmitis study coordinated 24 ophthalmology clinics/units across Europe to gather data. Researchers in this partially masked, placebo-controlled, randomized clinical trial enrolled 13,698 participants to evaluate the prophylactic effect of intracameral cefuroxime injection and/or perioperative levofloxacin eyedrops on the incidence of endophthalmitis after cataract surgery.

Key Points:

• Use of intracameral cefuroxime at the end of cataract surgery significantly reduced the risk of postoperative endophthalmitis.
• The total reported cases of endophthalmitis were nearly 5 times less in groups that utilized intracameral cefuroxime compared to those that did not (OR, 4.59; 95% CI, 1.74-12.08; P = 0.002).
• Cases of microbiologically proven endophthalmitis were more than 5 times less in groups that utilized intracameral cefuroxime compared to those that did not (OR, 5.32; 95% CI, 1.55-18.26; P = 0.008).

The ESCRS endophthalmitis study earns its landmark status as it was among the trailblazers of endophthalmitis prophylaxis as it relates to cataract surgery. The results of the study influenced surgical technique in the following years and widened the discussion on how to best prevent endophthalmitis after cataract surgery.