Preclinical cataract masquerading as post-LASIK regression.

The purpose of this case report is to bring forth a rare clinical scenario where preclinical cataract mimics post-LASIK regression and to describe the role of aberrometry in detecting higher order aberrations (HOAs) and early lens changes. A 36-year-old female presented with blurring of vision since 1 year after having undergone an uneventful LASIK surgery 3 years prior. Corneal topography and aberrometry were within normal limits. Although the lens was morphologically normal on slit lamp examination, increased HOAs and lenticular density were detected. Since there were no cataractous changes, the patient was advised regular follow-up. A year later, the patient had developed lenticular changes along with a further increase in aberrations and worsening of scatter on densitometry. Increase in aberrations and lenticular density may serve as a marker for cataract development before clinically detectable lenticular changes. This report shows how preclinical cataract can mimic post-LASIK regression with a change in spherical and cylindrical power of the eye. This could result in patients undergoing re-correction in eyes where the primary pathology is in the lens.

Introduction

With an increasing number of patients undergoing refractive surgery today, there is a rise in the incidence of early cataracts.[123] Patients' complaints include ghosting of images with increased glare and reduced contrast even before lenticular changes are clinically detectable. These symptoms, which are secondary to a subclinical cataract, can mimic post-LASIK regression. If the subtle lenticular changes are not diagnosed on clinical examination or on aberrometry, there is a risk of the patient being considered for refractive re-correction.

Case Report

A 36-year-old female was referred to us for refractive error corrective surgery of the left eye (LE) for a possible regression following LASIK. Three years ago, the patient had a refraction of − 2.00 D/−2.25 D × 35° in the right eye (RE) and − 2.25 D/−2.25 D × 160° in the LE with a corrected distance visual acuity (CDVA) of 20/20 in both eyes (BEs). Ocular examination and aberrometry had been unremarkable in BEs. The patient underwent LASIK to correct the refractive error following which she was asymptomatic with a CDVA of 20/20 in BEs.

Three years after the surgery, she noticed a drop in the quality of her vision along with ghosting of images in BEs. Her refraction was found to be −0.5 D/−0.25 DC×60° in the RE and −2.25 D/−2.00 DC×100° in the LE. She was “diagnosed” to have regression and was referred to our center for corneal collagen cross-linking and re-corrective surgery. Her corneal topography was stable. Aberrometry was done with an undilated pupil using the iTrace wavefront aberrometer (Tracey Technologies, Houston, Texas). High internal aberrations [Figure 1a], especially spherical aberrations and trefoil were noted. Pentacam (Oculus GmBH, Wetzlar, Germany) showed increased lens density; however, the Pentacam nuclear staging (PNS) grading was 0 [Figure 1b]. There was no clinically detectable cataract on slit lamp evaluation as per the lens opacities classification system III grading system [Figure 1c].[4] Re-corrective surgery was deferred, as the corneal topography was stable. The patient was advised regular follow-up. At the 1-year follow-up, a nuclear sclerosis of Grade 1 was noted in the LE on slit lamp biomicroscopy [Figure 2a], the PNS value was 1 and densitometry on Pentacam showed a value of 20.1 suggestive of early cataractous changes [Figure 2b]. Spherical aberration, trefoil, and tetrafoil were found to be increasing [Figure 2c]. A decision was taken to go ahead with cataract surgery in the LE with a toric aspheric monofocal intraocular lens. Following cataract surgery, the patient had a CDVA of 20/20 with a significantly better quality of vision.

Figure 1

(a) iTrace aberrometry showing high internal aberrations, especially trefoil and spherical aberrations, (b) Pentacam lens densitometry showing increased lens density. The Pentacam nuclear staging value was 0, (c) Slit lamp photo showing no cataractous changes (lens opacities classification system III grading)

Figure 2

(a) Slit lamp photo showing nuclear sclerosis Grade 1, (b) Pentacam lens densitometry showing increased lens density and a Pentacam nuclear staging Grade of 1, (c) Increase in internal higher order aberrations, especially spherical aberration, trefoil, and tetrafoil on iTrace aberrometry

Discussion

In the last few years, there has been an exponential increase in the number of refractive surgeries being performed. Apart from ectasias and regression, cataract is an important cause for poor vision following refractive surgery.[23] A large number of these patients present with symptoms of glare and reduced contrast. A characteristic increase in higher order aberrations (HOAs) and scatter are seen, suggestive of what can be termed as “preclinical” lens changes, which can be detected using newer diagnostic modalities such as Scheimpflug imaging and ray tracing.[5] The clinical findings include (a) early lens opacities, (b) inability to accommodate, and (c) changing aberration profile, with increased spherical aberration and/or coma.

The Scheimpflug camera in the Pentacam (Oculus GmBH, Wetzlar, Germany) has a densitometer that objectively measures light scatter and grades cataracts according to the PNS system. This not only helps us to measure the increase in lenticular density but also is useful in serial follow-ups to detect progression.[6] The iTrace ray-tracing aberrometer helps to determine the source of aberrations, corneal, or lenticular. Both these diagnostic modalities have proved to be invaluable in quantifying the contribution of the crystalline lens to the increased aberrations.[5]

Our patient presented with poor visual quality and decreased contrast a few years after having undergone a refractive surgical procedure. Although there was no morphologically significant cataract, there were changes in the HOAs and on densitometry. The patient went on to develop a clinically significant cataract over a year. The increased HOA and lens density can serve as an early indicator of a “preclinical cataract” thereby leading to appropriate intervention to improve visual quality.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.