Contact lens-induced pseudo-dystrophy of the cornea?

The corneal stroma during contact lens wear

Recent technological advances have lead to novel descriptions of the microanatomy of the corneal stroma. In the first section of this review, these findings and the role they play in the maintenance of vital properties such as corneal transparency, mechanical strength, homeostasis, wound-healing response and metabolism are described. In the second part, contact lens induced stromal alterations such as acidosis, oedema, striae, thinning and opacities are reviewed as well as the more recently described phenomenon of microdot deposits and keratocyte loss with an emphasis on how lens wearing stromal effects can be minimised.

Lattice Dystrophy-like Localized Amyloidosis of the Cornea Secondary to Trichiasis

PURPOSE

To report a case of stellate and branching linear corneal stromal amyloid deposits secondary to trichiasis and the use of molecular genetic analysis to exclude lattice corneal dystrophy.

METHODS

Case report and review of the literature. A 30-year-old man with a history of chronic ocular irritation was found to have distichiasis, epiblepharon, and unilateral corneal amyloidosis indistinguishable from lattice corneal dystrophy. Screening of the TGFBI gene was performed to rule out a previously reported mutation associated with lattice corneal dystrophy.

RESULT

A corneal biopsy performed before presentation to the authors confirmed the presence of corneal amyloidosis. Screening of exons 4, 11, 12, and 14 in the TGFBI gene identified 2 previously reported polymorphisms, Leu472Leu and Phe540Phe, but no other coding region changes.

CONCLUSION

Corneal stromal amyloidosis clinically resembling lattice corneal dystrophy may be associated with trichiasis. The exclusion of a TGFBI-associated corneal dystrophy in this case, leaving trichiasis as the most likely cause of the corneal amyloid deposition, demonstrates the utility of molecular genetic analysis in confirming or refuting a presumptive clinical diagnosis.

Determination of Microdot Stromal Degenerations Within Corneas of Long-term Contact Lens Wearers by Confocal Microscopy

PURPOSE

To ascertain whether a relationship exists between the presence of microdot deposits within the corneal stroma of long-term contact lens wearers as seen by confocal microscopy and the contact lens wear time, material, or other patient variables.

METHODS

Thirty-six myopic patients with a 15- to 43-year history of hard, rigid gas-permeable, or soft hydrogel contact lens wear and 12 age-matched emmetropic or spectacle-corrected myopic volunteers were included in this study. The numerical density and size of microdot deposits within the anterior, mid, and posterior stroma were determined with the confocal microscope, and the data were subjected to multiple regression statistical analysis.

RESULTS

Microdot deposits were encountered throughout the entire depth of the corneal stroma in all contact lens wearers. None of the control subjects showed microdot deposits. The numerical densities and the size range of microdots were similar in each of the stromal layers (anterior, mid, and posterior), with total mean values (+/- SD) for each parameter being 65.1 x 10(3) +/- 26.9 x 10(3) dots/mm (range, 21.4 x 10(3) to 121.1 x 10(3) dots/mm) and 3.04 +/- 0.92 microm (range, 1.5-5.0 microm), respectively.

CONCLUSIONS

Microdot deposits may represent granules of lipofuscinlike material within the corneal stroma of long-term contact lens wearers, formed as a result of chronic oxygen deprivation and chronic microtrauma to the cornea. No one in the control group showed microdot deposits. Among the independent variables, soft contact lens wear time had the most profound influence on numerical microdot density and size in our statistical equations.

Anterior basement membrane corneal dystrophy and pseudo-unilateral lattice corneal dystrophy in a patient with recurrent corneal erosions

PURPOSE

To report the utility of genetic testing in the diagnosis and management of patients with suspected corneal dystrophies.

DESIGN

Case report.

METHODS

A 58-year-old man with a history of recurrent corneal erosions was diagnosed with bilateral anterior basement membrane dystrophy and unilateral lattice corneal dystrophy. All 17 exons of the TGFBI gene were screened for mutations previously associated with lattice corneal dystrophy as well as novel coding region changes.

RESULTS

No mutations were found in the 17 exons of the TGFBI gene. A nucleotide change in exon 6 (651C>G) did not result in a change in the encoded amino acid (Leu217Leu).

CONCLUSIONS

In cases of suspected TGFBI corneal dystrophies, genetic testing is a useful tool to confirm the clinical diagnosis. In this case of suspected unilateral lattice corneal dystrophy, screening of the TGFBI gene ruled out the diagnosis, raising the possibility that the corneal changes were related to the coexistent anterior basement membrane dystrophy.

Long-term contact lens wear induces a corneal degeneration with microdot deposits in the corneal stroma

OBJECTIVE

Confocal in vivo real-time microscopy was applied to study the corneal morphology in long-term contact lens wearers.

DESIGN

In a cross-sectional study, patients with a history of long-term contact lens wear underwent corneal confocal microscopy. The authors investigated 13 patients with a history of up to 26 years of soft contact lens wear, 11 patients with a history of up to 25 years of rigid gas permeable contact lens wear, and a control group of 29 normal subjects without a history of contact lens wear.

INTERVENTION

Scanning slit-confocal microscopy was performed with a 50x/1.0 NA water immersion objective. Corneal optical sections were recorded in real time without further digital processing and reviewed frame by frame.

MAIN OUTCOME MEASURES

Video frames selected from all corneal layers were evaluated qualitatively. The new finding of panstromal microdot deposits was quantitated in a scoring system ranging from 0 to 4+. Corneal endothelial cell densities were counted with the fixed frame technique.

RESULTS

Epithelial microcystic changes and alterations of endothelial cell morphology were found to a variable extent as described previously. A new finding was there were highly reflective panstromal microdot deposits in the corneal stroma. For this new disease, a scoring system ranging from 0 to 4+ was established. In the control group, 0 of 29 patients had stromal microdot deposits. In the soft contact lens group, 13 of 13 patients had panstromal microdot deposits with a mean score of 3.1 (range, 1-4), and in the hard contact lens group, 11 of 11 had a mean score of 1.9 (range, 1-4) for corneal microdot deposits.

CONCLUSIONS

With confocal microscopy, a new type of chronic stromal change has been observed in all subjects with long-term contact lens wear. Because subjects with soft contact lens wear had a more pronounced corneal degeneration than did subjects with gas permeable lenses, the authors assume the deposits to be induced by chronic hypoxia. The condition of stromal microdot degeneration as observed with confocal microscopy may be the early stage of a significant corneal disease, which eventually may affect large numbers of patients after decades of contact lens wear.

Deep corneal stromal opacities associated with long term contact lens wear

BACKGROUND

One male and three female long term contact lens wearers (mean age 30.3 years; range 26-33) demonstrated unusual deep corneal stromal opacities which were predominantly just anterior to Descemet's membrane. None had any history of corneal dystrophy. These opacities were more common centrally, but were also identified in the corneal periphery.

METHODS

All patients underwent routine ophthalmic examinations and, where appropriate, slit-lamp photography and specular microscopy.

RESULTS

Mean lens wear in years and hours per day was 14.3 (range 10-17) and 14.3 (range 12-16) respectively. Specular microscopy disclosed cell densities within normal limits (mean 3041.5 cells per mm2) and coefficient of variation of mean cell area; COV = 0.31. Refractive errors ranged from -12.25 D to +6.25 best vision sphere and all four subjects attained at least 6/9 Snellen visual acuity. The subjects' contact lens wearing history included low water content hydroxymethylmethacrylate (HEMA) contact lenses and high water content HEMA contact lenses. Stromal opacity density was observed to diminish over a period of months on cessation of contact lens wear in two cases.

CONCLUSION

The possible causes of these rarely reported opacities are discussed.

Mottled cyan opacification of the posterior cornea in contact lens wearers

PURPOSE

We studied patients who had mottled cyan-colored opacities of the cornea to better understand the cause and prognosis of this entity.

METHODS

We reviewed examinations of patients who had a mottled cyan opacification of the cornea. Risk factors, including contact lens wear and exposure to heavy metals, were analyzed. Clinical findings, pachymetry specular microscopy, and progression of the abnormality were noted.

RESULTS

Six patients who had a mottled cyan opacification at the level of Descemet's membrane were identified. These opacities were located in the peripheral and midperipheral cornea. All patients had bilateral findings, had visual acuities of 20/20 or better, and were asymptomatic. All patients had worn soft contact lenses bilaterally for periods ranging from seven to 14 years.

CONCLUSION

All patients had the similar clinical appearance of a mottled cyan opacification at the level of Descemet's membrane in the peripheral cornea. Long-term contact lens wear appears to be associated; however, the exact cause is unclear.

Deep corneal stromal opacities in long-term contact lens wear

In 32 patients with long-term contact lens wear (up to 19 years), deep whitish opacities directly adjacent to Descemet's membrane were seen in the central part of the cornea. These opacities were seen in soft hydroxyethylmethacrylate (HEMA) as well as in hard (polymethylmethacrylate, PMMA) contact lens wear. These conditions could reduce visual acuity. When contact lens wear was discontinued or when the HEMA or PMMA lenses were replaced by gas-permeable rigid lenses, the lesions gradually diminished and resolved completely in most patients. One possible cause of these opacities is an allergic reaction to thimerosal. Another possible cause is chronic anoxia of the corneal stroma and endothelium. Endothelial cell density was not abnormal, but there was a marked polymegethism of the endothelium as a sign of endothelial stress.