“Yes, I have a pair of eyes,” replied Sam, “ ‘and that's just it.
If they wos a pair o' patent double million magnifyn 'gas microscopes of hextra power,
p'raps I might be able to see through a flight o'stairs and a deal door;
but bein' only eyes, you see my wision's limited.”
Cataract surgery is carried out invariably as a monocular procedure. Second-eye cataract surgery is variously performed at intervals of 5 minutes, 24 hours, 1 week, and 1 month or deferred indefinitely. Local or national health care provisions together with individual surgeon and, of course, patient preferences determine the intersurgery interval, assuming patients have bilateral operable cataracts.
There are 2 main indications for cataract surgery: to clarify a clouded light path and to grasp the opportunity to permanently correct ametropia. Given the latter indication, it would be indefensible to defer second-eye surgery.
Second-eye surgery represents a substantial part of the total cataract surgery volume. In this issue, Lundstrom and coauthors note several reasons for the increasing frequency of second-eye surgery. They cite Laidlaw et al.,1 who note that factors include an aging population and major advances in surgical and anesthetic techniques. However, the disability that follows unilateral cataract surgery includes disturbed motion perception2 and stereoacuity,3 not to mention anisometropia.
Rationing surgery in hard-pressed health care systems dictates that more patients will be treated and therefore presumably benefit from a 1-eyed approach to the economic problem. But it can be argued that efficient organization, economies of scale, and bilateral simultaneous surgery would make health care currencies go further.
Lundstrom and coauthors' conclusion from their Catquest outcomes study is hardly earth shattering. Much earlier, Javitt et al.4 concluded that patients who had surgery in both eyes reported greater improvement in subjective visual function than those who had surgery in 1 eye. There was a benefit associated with restoring binocular vision in that population. Thus, the findings support a policy recommendation—that cataract surgery in both eyes remains the appropriate treatment for patients with cataract-induced visual impairment.
Elderly patients with cataract suffer subtle visual disabilities, such as reduced spatial resolution,5 limited contrast discrimination,6 impaired stereo depth perception,7 reduced reaction time as illuminance varies, and light and dark adaptation problems.8 Vision is not reading a Snellen chart, which is a relatively poor benchmark. Such measurements take place in a static situation while observing a high-contrast chart and under variable ambient illumination. It is a curious paradox that good Snellen acuity may belie the real situation in which vision is compromised by any or all the above factors. Add binocularity and the case for cataract surgery to both eyes is irrefutable—a decision uncluttered by the need for too much contemplation. There is no moral dilemma or need for a casuistic approach.
Two men look out through the same bars:
One sees mud, and one the stars.
1. Laidlaw DAH, Harrad RA, Hopper CD, et al. Randomised trial of effectiveness of second eye cataract surgery. Lancet 1998; 352:925-929
2. Scotcher SM, Laidlaw DAH, Canning CR, et al. Pulfrich's phenomenon in unilateral cataract. Br J Ophthalmol 1999; 81:1050-1055
3. Talbot EM, Perkins A. The benefit of second eye cataract surgery. Eye 1998; 12:983-989
4. Javitt JC, Brenner MH, Curbow B, et al. Outcomes of cataract surgery; improvement in visual acuity and subjective visual function in the first, second, and both eyes. Arch Ophthalmol 1993; 111:686-691
5. Sloane ME, Owsley C, Alvarez SL. Aging, senile miosis and spatial contrast sensitivity at low luminance. Vis Res 1988; 28:1235-1246
6. Richards OW. Vision at levels of night road illumination; night visibility. Washington DC Highway Research Road Bulletin No 56, 1952; 36-65
7. Allen MJ. Vision & Driving—Traffic Safety, 1969; 8-9, 38-40
8. Campbell FW, et al. Bad light stops play. Ophthalmic Physiol Optics 1987; 7:165-167