Comment on: Optimizing the inter-eye transition to improve immediately sequential bilateral cataract surgery comfort

Balian et al. prospectively surveyed 200 patients undergoing immediately sequential bilateral cataract surgery (ISBCS) and found a consistent “second-eye penalty”: The second procedure was rated as more painful and less comfortable, and perceived as longer despite comparable operative times.¹ Although absolute pain was low, the effect was robust: mean pain increased from 0.935/10 (first eye) to 1.475/10 (second eye; P < .001). In ordinal regression, second-eye surgery was 4.48 times more likely to be rated as more painful, while operative duration was also modestly associated with pain (odds ratio [OR] 1.11 per additional minute; P = .008). Because operative duration contributes yet is similar between eyes, the residual second-eye effect may reflect nonoperative, between-eye factors—making the intereye transition a practical target to improve experience without altering the phacoemulsification technique.¹

One nuance is confounding by indication. The nonsignificant association between additional medication before the second eye (“top-off”) and higher reported pain (OR 1.84; P = .35) may reflect rescue dosing triggered by early distress rather than an effect of supplementation itself. Analytically, treating top-off as a response to evolving intraoperative anxiety/sympathetic activation, and capturing baseline anxiety or physiologic markers, could better estimate any true benefit of supplementation. The heterogeneity of “other” medications, including nonanalgesic agents (eg, ephedrine, labetalol, phenylephrine, and ondansetron), further supports careful modeling of indication and timing.¹

Independent of this analytic issue, “second eye” may also proxy cumulative ocular surface and periocular discomfort that increases across the visit. Because intereye interval and topical/intracameral redosing timing were not measured, this mechanism is necessarily hypothesis-generating. In ISBCS, the interval from initial topical anesthesia and antisepsis to second-eye speculum placement is inevitably longer than for the first eye. Conjunctival and eyelid nociception (drape tension and speculum pressure), povidone–iodine–related irritation, and ocular-surface desiccation from microscope light and room airflow may accumulate over time, which are effects not captured by per-eye operative duration. In addition, irritation from the freshly operated first eye may contribute to a higher global discomfort baseline during the second eye, lowering the threshold at which manipulations are perceived as painful.

A complementary explanation is cognitive rather than purely nociceptive. Because the questionnaire was administered only after completion of the second eye, comparative responses may be influenced by recency and the “peak-end” principle: Retrospective evaluations overweight the most intense and final moments of an experience while often neglecting duration.² In a same-day bilateral workflow, the second eye is literally the “end” of the entire encounter; even modest late discomfort could disproportionately shape the overall remembered quality of ISBCS.

These mechanisms suggest a pragmatic, testable “between-eye reset”: Deliberate relubrication, repeat topical anesthetic immediately before second-eye speculum placement, confirmation of adequate intracameral anesthesia, and timing any systemic anxiolysis/analgesia to peak before the second eye—implemented within standard ISBCS strict aseptic separation. Prospective work should record intereye interval and medication timing and capture pain at standardized milestones (eg, speculum placement, incision, and phacoemulsification), not only post hoc comparisons. Second-eye pain has been reported in delayed sequential cataract surgery as well, but ISBCS uniquely concentrates both physiologic accumulation and end-of-encounter cognitive weighting into 1 visit; optimizing the intereye transition may therefore yield outsized gains in patient experience.^3,4