Lattice corneal dystrophy: Visual outcomes with scleral lens

INTRODUCTION

Lattice corneal dystrophy (LCD) is a rare, inherited condition that primarily affects the cornea of the eye, leading to progressive vision loss due to the accumulation of amyloid deposits. These deposits appear in a distinctive “lattice-like” pattern, hence the name, and are typically located in the central part of the cornea, while the peripheral cornea tends to remain unaffected. The amyloid deposits disrupt the corneal structure, leading to opacity and diminishing the clarity of vision over time.

Type I LCD, also known as Biber-Haab-Dimmer dystrophy. It is autosomal dominant and results from mutations in the transforming human growth factor beta-induced (TGFBI) gene. It is usually present in the first or second decade of life.^[1,2] LCD type I is caused by mutations in the TGFBI gene, located on chromosome 5 at locus 5q31.^[1,2] This gene is also called BIGH3.^[3,4]

Scleral lenses (SL) are designed to vault over the entire corneal surface, resting on the sclera. These lenses offer correction of visual symptoms caused by a variety of ocular surface diseases and corneal ectasias. A fluid reservoir (FR) forms between the lens and the cornea, smoothing surface irregularities, providing relief for those with ocular surface disease, and allowing for healing of the ocular surface. Primary indications for use of SL includes ocular surface disease, corneal irregularity, and severe refractive error.

CASE REPORT

A 40-year-old male presented with chief complaints of diminution of vision, photophobia and a history of LCD Type I (LCDI). The patient reported working as a data Analyst. Before arrival, he had been advised of penetrating keratoplasty (PK) from a corneal specialist. The patient was adamant about avoiding surgery, yet had extremely specific standards for his visual performance. On presentation, the patient’s uncorrected visual acuity was 6/60 eff in both eyes, and best corrected visual acuity was 6/24 with +3.50D in OD and 6/24 with +3.00 Ds in OS. Slit-lamp examination of both eyes (OU) reveals lattice-like lines in the stromal layer that spread from the central cornea toward the periphery, suggestive of LCD [Figure 1a]. Anterior-segment optical coherence tomography was performed to confirm the disruptions in the Bowman’s and anterior stromal layers, and pachymetry revealed OD:618 microns, OS:648 microns, showing increased thickness and diagnosed as LCD Type I [Figure 1b]. The patient was educated that disease progression had occurred and would likely continue. Additional education included the possibility of PK and LL with ECCC/IOL+ in the future, but he was reassured that the best vision and comfort would be found using SL. The patient was then fitted with a 16.50 mm SL, which was vaulting the cornea with 2.8 sag in OU [Figure 2]. Adequate central vault of around 300 microns, good coverage, centration with good haptics of no blanching and edgelift were achieved, with which the patient’s visual acuity (VA) was 6/7.5 in OU, also photophobia was reduced with good comfort. The patient was very much motivated for SL in OU.

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Figure 1: (a) Both eyes: Diffuse slit lamp image showing lattice –like lines from central cornea. (b) Anterior segment optical coherence tomography image of both eyes showing increased pachymetry and disrupted stromal layers.

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Figure 2: (a) Right and (b) left eye show the image of scleral lens fitting with good centration and good haptic.

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DISCUSSION

The symptoms of corneal dystropy bascially depends on which specific type you have. Few candidates never have any symptoms at all. However, when symptoms develop, they usually affect both eyes and progressively get worse with time. The cornea, likely a meticulously crafted piece of glass, plays a pivotal role in how we see the world. Its clarity and curvature are essential for refracting light properly onto the retina, enabling sharp vision. However, corneal dystrophies can change that, however, they disrupt this delicate equilibrium. These are often genetic conditions that lead to the accumulation of abnormal materials, whether lipids, proteins, or other deposits in the cornea’s layers. Corneal dystrophies, however, disrupt this delicate equilibrium. These are often genetic conditions that lead to the accumulation of abnormal materials such as lipids, proteins, or other deposits, in the cornea’s layers. That makes symptoms such as as the corneal deposits increase, they can scatter light passing through the cornea, resulting in blurry or distorted vision, photophobia associated with deposits, and structural changes in the cornea. In addition to the lattice-like opacities, recurrent epithelial erosions are a common complication of LCD. These erosions occur when the outermost layer of the cornea (the epithelium) becomes damaged, causing pain, irritation, and further vision impairment. These erosions can appear even before the characteristic stromal deposits become noticeable, adding to the challenges of early diagnosis,^[1,3,5-7] corneal surface irregularities may lead to gritty sensation. Surface irregularities lead to higher order aberrations (HOAs) where patients complain of halos, glare, ghost images, and difficulty during night drives. Previous studies have reported the utilization of SL in improving VA,^[8,9] Contrast sensitivity,^[10,11] and reducing HOAs^[11,12] in irregular or ectatic corneas. Yagi-Yaguchi et al., in `their retrospective study, reported that a large amount of HOAs in LCD when compared with other dystrophies.^[13] Recognizing and addressing these symptoms early can significantly improve quality of life for individuals with LCD. There are limited studies on LCD and SL. This case report aims to deliver that SLs are an excellent management option for individuals with LCD, particularly when visual distortions and corneal irregularities cannot be adequately corrected with glasses or standard contact lenses. These large-diameter lenses vault over the cornea and rest on the sclera, offering unique benefits for those with LCD. SL creates a smooth, uniform optical surface that compensates for these irregularities, improving visual clarity and reducing distortions. The custom design of SL minimizes refractive errors and light scatter caused by corneal deposits, enhancing vision quality by reducing HOAs. SL protects the cornea by creating a FR between the lens and the cornea. This FR promotes healing, prevents further damage, and reduces the chances of recurrent corneal erosions, also keeping the cornea hydrated, reducing symptoms of dryness and irritation.

CONCLUSION

SL provides excellent symptom management and visual improvement, they are not a cure for LCD. They should be part of a comprehensive treatment plan that may also include lubricating drops, treatment for recurrent erosions, or surgical interventions (e.g., phototherapeutic keratectomy or corneal transplant) in advanced cases. Regular follow-ups with an ophthalmologist or contact lens specialist are essential to monitor both the progression of LCD and the fit and function of the SL.