Who will benefit most from cataract surgery?

A team of researchers from Denmark believes it has found a way for ophthalmologists to identify the patients who will most likely to benefit from age-related cataract surgery.

Additionally, the scientists defined cataract surgery as beneficial if it led to an improvement in visual acuity or visual function without major perioperative or postoperative complications.

Top med school regrets

In a review article recently published in Acta Ophthalmologica, they recommended that the Swedish NIKE (Nationell Indikationsmodell för Katarakt Ekstraktion) system be adopted in Denmark. “We found that the Swedish NIKE system (Lundström et al. 2006) was the only system with a documented association between preoperative grading and outcome after cataract surgery,” they wrote.

Items included in the NIKE indication tool, according to the 2006 study:

·  Visual acuity, surgery eye

·  Visual acuity, fellow eye

·  Patient’s perceived difficulty in performing day-to-day activities

·  Cataract symptoms (glare, difference between the eyes)

·  Ability to live independently (work, driving, home help, caring for relatives, etc.)

·  Medical⁄ophthalmic reasons for urgent surgery

The NIKE system, adapted for Swedish use from the Canadian Cataract Priority Criteria Tool, has been used by all ophthalmic clinics in Sweden since late 2005, according to the 2006 report. A study published in 2014 by Ng and Lundström found that using the NIKE system to prioritize patients waiting for cataract surgery also “reduces waiting times for those with the greatest need.”

Next: What research ultimately revealed

The recent investigators’ quest stemmed from and was funded by a Danish Health and Medicines Authority initiative to set evidence-based national guidelines for the surgery. The goal of their meta-analysis and systematic review, they say, “Was to determine which preoperative characteristics best predict the visual gain, both subjective and objective, after cataract surgery in order to ensure that cataract surgery is offered to the patients who are most likely to benefit from surgery.” The results are timely, they add, because people are seeking cataract surgery at younger ages and with better vision than in years past-in an effort to maintain a high level of vision and because of the surgery’s increased success and safety.

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Their literature search ultimately revealed eight observational studies comparing cataract surgery outcomes in patients who had poor and fair preoperative visual acuity. Four of these studies compared postoperative visual acuity in the patients, and four of the studies compared the subjective visual outcome after cataract surgery in patients who had poor or fair preoperative visual acuity.

“We also wanted to compare the outcome after cataract surgery in patients who were characterized by a combination of preoperative visual acuity findings and preoperative subjective visual function, but we could not find any studies that fitted the inclusion criteria,” the authors wrote. “We found that preoperative visual acuity was a poor predictor for postoperative visual function. This finding is perhaps not surprising as postoperative visual function depends more on the status of the retina and optic nerve than on the degree of the cataract that is removed.”

Currently used testing methods and the issues associated with them as predictors of surgical success, according to the researchers:

·      Objective measurements such as dynamic light scattering or straylight, Scheimpflug photography, the correlation between phaco time and energy, and visually based grading systems do not accurately predict surgical outcomes.

·      The preoperative status of the retina and optic nerve is difficult to assess before surgery.

·      Vision tests, including the critical flicker frequency and optimal reading speed, potential acuity meter and laser interferometry, are limited in their ability to predict success.

Next: Hope for findings

“Cataract surgery is the most commonly performed elective surgical procedure in many westernized countries, and yet we have very little scientific data to help the clinician to decide when to offer cataract surgery to an individual patient,” the authors wrote. They hope their findings will assist ophthalmologists and patients in making decisions related to the surgery.