This is a challenging case, and the patient’s expec-tations of further surgery should be in line with thedecreased predictability another surgical procedurewould give.

DAVID R. HARDTEN, MDVRUSHALI V. GOSAVI, MD

Minneapolis, Minnesota, USA

f I believe this patient has an ablated area that isdecentered upward and over 10 months has acquiredinduced irregular astigmatism. Management of this caseshould involve a further period of observation untilfull topographic stability of the cornea has occurred,after which a full topographic and aberrometric exami-nation should be done, the flap lifted, and wavefronttreatment performed, preferably using the Visx Wave-Scan system.

PATRICK I. CONDON, MCH, FRCS FRCOPH

Waterford, Ireland

f Preoperatively in the left eye, the refraction was�5.00 �1.50 � 175 with and without cycloplegia, theK-value was 44.2 D, the UCVA was 20/100, and theBCVA was 20/20. As a child, the patient had squintsurgery, perhaps in the left eye. Postoperatively, theUCVA is 20/50 and the BCVA, 20/40 with�0.25�1.25 � 85. A BCVA of 20/20 is obtained onlywith a hard contact lens of �0.50 D.

The Orbscan topography shows a slight decentra-tion in the left eye from the pupillary area upward. At 10months, there was irregularity in the middle of thecornea.

To manage this case, I would first consider aTopolink procedure in an attempt to smooth the hyper-opic decentration and enlarge the optical zone. The goalwould be to improve the UCVA and BCVA.

Another option is a wavefront-guided ablation. Iwould elevate the flap to see a slightly rough surface ofthe lasered area of the stromal bed and would correct theslight decentration in a secondary 2-step procedure.First, I would ablate the refractive error and second,perform a wavefront ablation. Because the decentrationis slight, both steps would be difficult to perform. Inaddition, reopening the flap could induce unknown ab-errations and small flap irregularities. These in turncould cause new aberrations and decrease the BCVA andUCVA.

In summary, my first choice in managing this casewould be to correct the slight decentration with aTopolink ablation to enlarge the optical zone andsmooth the central surface with the hope of improvingthe BCVA and UCVA. KLAUS DITZEN, MD

Weinheim, Germany

f Because of several complex and unresolved issues,LASIK is still a more challenging procedure in hyperopicpatients than in myopic patients. In general, hyperopicLASIK outcomes are related to (1) the effect of preoper-ative, intraoperative, and postoperative oculomotor andaccommodative conditions on the target refraction andthe alignment, assessment, and tolerance of the vertexcorrection induced by the photoablation and (2) theeffect of the keratorefractive procedure on monocularand binocular visual performance.

In this case, the very large optical zone (7.0 mminstead of the more common 5.5 or 6.0 mm) the sur-geon chose because of a large scotopic pupil (6.5 mm)implies a deeper ablation (140 �m) and thinner flap(160 �m) than usually attempted. The suboptimal vi-sual outcome (UCVA improved from 20/100 to 20/50but BCVA reduced from 20/20 to 20/40) suggeststhat the optical performance of the cornea was al-tered. Most likely, irregular astigmatism and higher-order aberrations were induced by the surgery becausethe BCVA can be improved to 20/20 with a rigid con-tact lens and the residual refraction is close to em-metropia (�0.25 �1.25 � 85).

Marked upward decentration of the optical zone isseen on the Orbscan axial curvature map (Figure 2) at 10months (lower left map) so that the visual axis is close tothe lower edge of the optical zone. This decentered ab-lation would be more precisely documented by an Orb-scan differential anterior elevation map (postoperativeminus preoperative) as individual elevation maps (upperleft map) only provide height information relative to afloating reference sphere.

Other potential causes of the degraded optical per-formance of the cornea in this case include dry eye; flapfolds induced by the combination of a thin flap, deepablation, long procedure, and steep stromal bed, whichwould require diagnosis by a retroillumination photo-graph; and changes in the curvature of the posteriorsurface of the cornea (ectasia), which differential analysisof the posterior elevation maps could help diagnose.

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Multifocality induced by the shape of the hyperopicablation profile may also affect visual performance. Thehyperopic ablation profile creates a large positivespherical aberration, which means that the refractionand image quality will greatly depend on pupil size.Preoperative topography of the refractive error overthe entrance pupil may exacerbate this problem.

Conventional refraction methods using manifestrefraction, fogging, or retinoscopy techniques mightnot accurately measure the preoperative or postoper-ative refractive error in hyperopia. Using predictedphoropter refraction derived from ZyWave aberrom-eter wavefront analysis, we can determine that thepreoperative hyperopic refractive error measuredthrough a noncycloplegic dilated entrance pupil is in-herently related to pupil diameter. This means that al-though some patients may have a homogeneousrefractive error over a 6.0 mm pupil (eg, �3.00 D), mostwill have more pronounced hyperopia in the central3.0 mm zone and a less pronounced hyperopia in theperiphery.

Because of the Stiles-Crawford effect, the manifestor “objective” refraction measured by conventionaltechniques provides only an average value of the refrac-tive error over the entrance pupil. Applying a “monofo-cal” standard correction to this average value risksovercorrecting the periphery (creating night myopia)and undercorrecting the center (leaving residual pho-topic hyperopia). The rate of change in the refractiveerror from the center to the periphery varies by individ-ual. For most hyperopic patients, this would require acustomized ablation approach based on the topographyof the refractive error.

Although the patient’s oculomotor condition mayhave affected intraoperative centration of the ablation, itis unlikely that it affected postoperative visual acuity. Inany case, the tolerance to the vertex correction at-tempted by LASIK should be tested routinely using pre-operative contact lenses. This is usually sufficient tounmask problems related to the removal of the prismatic

effect associated with prescription glasses. This is alsouseful in ascertaining whether a degree of monovision(overcorrection in the nondominant eye) might be at-tempted to compensate for some of the presbyopia inpatients older than 40 years.

This patient should be given adequate informationon the nature of the limiting factors involved in thevisual outcome and the possibility that the optical qual-ity of the cornea may spontaneously and slowly improvewith time because of resolution of the ocular surfacedryness, epithelial and stromal remodeling associatedwith wound healing, improved transparency of the in-terface, and sensorimotor adjustments of the visual axiswithin the entrance pupil.

Additional workup in this case should include dif-ferential analysis of anterior and posterior elevationmaps, retroillumination assessment of the flap, andwavefront analysis with a determination of the refractiveprofile over the entrance pupil. Fitting a rigid gas-per-meable contact lens would provide a transition periodfor an additional 6 months, at which time surgical man-agement can be considered.

Surgical enhancement would include lifting andstretching the flap with extreme care to maintain theintegrity of the epithelial margins to prevent epithelialinvasion and recentration of the optical zone using atopography-guided approach rather than an aberrom-etry-guided approach. The technology of topography-guided ablation for hyperopic profiles has been availablefor at least 1 year with the Mel 80 (Meditec) and Wave-light Allegretto (Lumenis) devices; however, the safetyand efficacy of such an approach have not yet been re-ported in the peer-reviewed literature.

Wavefront-guided ablation for hyperopic profilesmay ultimately be of interest in such cases. This tech-nique is being investigated using the Bausch & LombKeracor 217 Z device, which is not commercially avail-able at this time.

MICHAEL ASSOULINE, MD, PHDParis, France

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