ENHANCEMENTS AFTER CATARACT SURGERYJORGE L. ALIO; AHMED A. ABDELGHANY; ROBERTO FERNENDEZ-BUENAGA

ABSTRACTANDINTRODUCTION

ABSTRACT

INTRODUCTIONCataract removal with IOL implantation one of the most frequently performed surgical procedures in clinical practice.Modern microsurgical techniques, new IOL technologies, sophisticated biometric methods and advanced methods of IOL power calculation HIGH-QUALITY VISIONIn a multinational cataract surgery population consisting of over 360.000 cataract extractions:92,6% achieved improved corrected distance visual acuity5.7% were unchanged1,7% had worse corrected distance visual acuity after surgery.

Advances in small incision surgery have enable cataract surgeon to progress from being concerned primarily with the well tolerated removal of the opaque crystalline lens to a procedure refined to yield the best possible postoperative refractive result.Refractive considerations are integrated in modern cataract surgery, and emmetropia the aim in the majority of cataract cases today in a recent report analyzing refractive data of over 17.000 eyes after cataract surgery emmetropia was only achieved in 55% of eyes in which it was targeted

Residual postoperative astigmatism is not uncommon.A physiological astigmatism of up 1 D either with or against the rule may be useful to increase the depth of focus under routine conditions, and may increase the quality of vision in daily life.Astigmatism of up to 1 D may also be considered a physiological measure to reduce uncorrected presbyopia for eyes with intact retina and optic nerve.Uncorrected corneal astigmatism pseudophakic eyes significantly affects through-focus performance of presbyopia-correcting IOLs.Although multifocal IOLs increase depth of focus this benefit diminishes when over 0.75 D of astigmatism remains uncorrected.

The use of multifocal IOLs has recently become a popular alternative to monofocal IOLs in patients who do not want to wear spectacles after cataract surgery or after refractive lens extraction.Image quality in patients implanted with multifocal IOLs diminishes when over 0.75 D astigmatism remains uncorrected They may also suffer from a severe decrease in quality of vision due to blurred vision, glares, halos, photophobia and diplopia, and can benefit considerably from an IOL exchange.This leads to a significantly improved corrected visual acuity, both for distance and near vision.

The main drawback of multifocal IOL exchange to a monofocal IOL is the reduction in spectacle independence for reading.When spectacle independence is important, monovision with a precalculated myopic deviation may be also an option.Despite new advances in cataract surgery, unsatisfactory visual outcome, mainly due to residual refractive error, occasionally occurs. This has led us to review the causes of patients dissatisfaction after cataract surgery and the possible approaches for enhancement after cataract surgery.

CAUSES OF UNSATISFACTORY VISUAL OUTCOME AFTER CATARACT SURGERY

RESIDUAL REFRACTIVE ERRORThe most frequent complication following cataract surgery

MULTIFOCAL INTRAOCULAR LENS VISUAL EFFECTSHowever, even if emmetropia is reached, patients implanted with multifocal IOLs may suffer from a severe decrease in quality of vision due to blurred vision, glare, halos, photophobia and diplopia.The most important parameter regarding quality of vision probably the orientation of the photoreceptors (Stiles-Crawford effect) the parameter of which is even more difficult to objectify preoperatively and postoperativelyResidual ametropia and astigmatism, posterior capsule opacification and a large pupil were the three most significant etiologies

INTRAOCULAR LENS MALPOSITIONTilt and decentration of IOLs result in defocusing, astigmatism and wavefront aberration.It may occur early postoperatively due to inadequate capsular support or later secondary to capsule contraction and capsulorhexis phimososLate IOL dislocation remains anunusual complication after cataract surgeryPseudoexfoliation has always been the most recognized predisposing factor for late dislocation, and a recent series highlighted that high myopia is an important risk factor for the late in-the-bag serious IOL dislocation after uneventful cataract surgery.Furthermore, dislocation in high myopia occurred at a younger age than in pseudoexfoliation, hence affecting patients with higher visual demands.

ENHANCEMENTS (TOUCH UP) AFTER CATARACT SURGERYThere are different methods that can be used to resolve these unsatisfactory situationsWhen a secondary procedure is performed for the correction of refractive error REFRACTIVE ENHANCEMENTWhen it is performed for other visual problems NONREFRACTIVE ENHANCEMENT

ENHANCEMENTS (TOUCH UP) AFTER CATARACT SURGERY

TORIC INTRAOCULAR LENS ROTATIONCan be used when excess manifest refractive cylinder leads to an unacceptable level of unaided vision in a patient after toric IOL implantation.IOL rotation should be the preferred choice if the surgeon:Expects the rotation to reduce the manifest refractive cylinder to an acceptable level,Knows how much and in which direction to rotate the IOLCapable of performing the desired rotationIn some cases, IOL rotation will not result in a significant reduction in the which case nonlens ocular residual astigmatism is likely to be present unless there has been an incorrect selection of the toric IOL LASIK to target plano and correct for the refractive surprise.

CONCLUSIONLASIK has proved to be the most accurate procedure to correct residual refractive error after cataract surgery.IOL-based surgical procedures are less predictable and should be selected according to the problem.IOL exchange is preferred in patients implanted with multifocal IOLs, suffering from a severe decrease in quality of vision.Piggyback IOLs are preferred mainly for the correction of high residual refractive error after cataract surgery when LASIK is not available.Toric IOL rotation can be used for excess residual manifest refractive cylinder.

KEY POINTSLASIK proves to be a viable, noninvasive and the most accurate procedure to correct ametropia after cataract extraction with IOL implantation.Piggyback IOLs should be used mainly for the correction of high residual refractive error after cataract surgery.IOL exchange is the preferred technique when the clinical correction of the residual refractive error is not effective in the improvement of the visual symptoms in patients implanted with multifocal IOLs.Lens exchange with scleral-fixated IOL can be used for the management of late in-the-bag IOL dislocation.Toric IOL rotation or LASIK can treat residual excess manifest refractive cylinder