I have personally observed a phenomenon for the past two decades that has now been formally studied.  First, patients undergoing surgery under mild sedation are more likely to tell you during surgery that they are more awake during the second procedure compared to the first or that “I didn’t remember any of this during my first eye.”  I believe this is the phenomenon of subliminal recall in that certain procedures are “below” memory threshold and the repetition brings this into their recollection through reinforcement.  Second, their is a perception that the second eye heals more slowly and given an equal healing scenario, the first eye is usually the worse eye and also compared postoperatively to the remaining cataract in the second eye giving a “wow factor” of great improvement.  The second eye is then compared to the already healed first eye giving less of that sense of amazement and may even be a little bit of a let down.  There may also be a loss of some monovision in cases were the second eye may have been giving some reading vision and is now brought up to match the distance vision in the first eye.  Patients are “wired” to observe and point out what they are missing or what they have lost to a greater degree than what they have gained.  So a mild cataract in myopic patient who now is emmetropic – for distance – will likely be aware that there is more of a need for reading glasses – even with the “presbyopia treating” intraocular lenses.  Finally there is the second eye phenomenon of greater pain observed in the second eye that we all observed with the mechanical microkeratome for LASIK – greatly improved now with the Femtosecond Laser.  This may also be related to the new study (J Cataract Refract Surg.2011;37(6):1009-1014.) addressing increased pain reported during second eye cataract procedures possibly related to reduced anxiety.  To learn more:

A subtle increase in pain during a patient’s second cataract extraction relative to the first may be associated with decreased preoperative anxiety, a study found.

“Having enjoyed a successful first cataract extraction, a portion of patients may subsequently approach their second cataract extraction with less trepidation but also an expectation of less pain. Any pain they experience is then perceived as significant,” the study authors wrote.

The prospective, single-masked, longitudinal trial included 65 patients who underwent bilateral cataract surgery and completed the Amsterdam Preoperative Anxiety and Information Scale, the preoperatively administered State-Trait Anxiety Scale and two visual analogue scale pain surveys administered twice postoperatively.

The median visual analogue pain score for the first cataract surgery was 0 on a scale of 0 to 10. The median score for the second extraction was 1, with 40% of patients reporting higher scores for their second operation. This difference was no longer evident by postoperative day 1.

An increase in reported pain was associated with a lower level of preoperative anxiety prior to the second procedure.

“We recommend preoperative counseling for all patients before their second cataract extraction, cautioning that the more relaxed they are this time, the more unexpected and heightened any pain may feel,” the study authors wrote.

Lower levels of anxiety may be explained by the amnestic effects of benzodiazepines during the first surgery, which may cause patients to present to the second operation with expectations of heavy sedation, the study authors said.