Perceived Cataract Surgery Pain Predictable With Iris Vessel Area Density, Interval

Perceived cataract surgery pain scores for patients undergoing second eye cataract removal correlate with a combined evaluation of preoperative iris vessel area density (VAD) and the time interval between procedures, according to research published in the Journal of Cataract & Refractive Surgery. This equation can be used to determine the optimal timing for second-eye cataract surgery to avoid intraoperative pain.

The case-controlled phase of the study enrolled 70 patients between 40 and 80 years of age who underwent phacoemulsification at Shanghai General Hospital. Patients in the first eye surgery group (n=35) and second-eye surgery group (n=35) did not significantly differ in baseline characteristics. Patients in the second-eye surgery group reported significantly higher perceived cataract surgery pain scores compared with patients in the first-eye group (P =.0005). Preoperative iris VAD was significantly associated with pain scores (P =.0047).

The prospective cohort phase of the study evaluated the predictive value of preoperative iris VAD on pain scores. The cohort of second-eye surgery patients were divided by VAD values into a low VAD group (VAD <0.2167; n=81) and a high VAD group (VAD ≥0.2167; n=43). Perceived cataract surgery pain scores for the high VAD group were significantly higher compared with the low VAD group (P =.0012). When combined with interval between surgeries, the negative predictive value for whether the patient experienced significant pain (pain score >3) was 0.95. The positive predictive value was 0.29 with a sensitivity of 97% and specificity of 23%.

These results quantitively verify anecdotal evidence that patients who undergo a second surgery for bilateral cataracts experience more pain than the first surgery despite equivalent conditions for both procedures.

A possible explanation for this observation is sympathetic uveitis in the second eye, which may increase the level of inflammation. The authors hypothesize, “the degree of preoperative iris VAD elevation reflects the level of subclinical sympathetic uveitis in the eye. Patients with higher levels of inflammation experienced more pain during the second eye surgery. Thus, in the case of low iris vasodilatation, the patient’s intraoperative pain will be relieved, and a second eye surgery can be considered to increase the patient’s surgical comfort.”

The study did not evaluate inflammatory factors in the aqueous humor to verify the relationship between inflammation and VAD. The results could also be affected by confounding factors such as variable pupil and light conditions and comorbid diseases that may elevate systemic inflammation.