In vivo Imaging of Reis-Bücklers and Thiel-Behnke Corneal Dystrophies Using Anterior Segment Optical Coherence Tomography

From bench to clinic: Emerging therapies for corneal scarring

Corneal diseases are one of the leading causes of moderate-to-severe visual impairment and blindness worldwide, after glaucoma, cataract, and retinal disease in overall importance. Given its tendency to affect people at a younger age than other blinding conditions such as cataract and glaucoma, corneal scarring poses a huge burden both on the individuals and society. Furthermore, corneal scarring and fibrosis disproportionately affects people in poorer and remote areas, making it a significant ophthalmic public health problem. Traditional medical strategies, such as topical corticosteroids, are not effective in preventing fibrosis or scars. Corneal transplantation, the only effective sight-restoring treatment for corneal scars, is curbed by challenges including a severe shortage of tissue, graft rejection, secondary conditions, cultural barriers, the lack of well-trained surgeons, operating rooms, and well-equipped infrastructures. Thanks to tremendous research efforts, emerging therapeutic options including gene therapy, protein therapy, cell therapy and novel molecules are in development to prevent the progression of corneal scarring and compliment the surgical options currently available for treating established corneal scars in clinics. In this article, we summarise the most relevant preclinical and clinical studies on emerging therapies for corneal scarring in recent years, showing how these approaches may prevent scarring in its early development.

The observation of anterior segment in children with an R124L mutation corneal dystrophy by anterior segment optical coherence tomography and in vivo confocal microscopy

Purpose

To evaluate the anterior segment in children with an R124L mutation corneal dystrophy (CD) using anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM).

Methods

We investigated a family with prevalent CD and an R124L mutation; 59 individuals (14 patients; 6 male and 8 female, aged 2–69 years, 6 children, 2:4 male: female ratio) from four generations were included. We observed corneal lesions through ophthalmologic examinations, AS-OCT, and IVCM. The mean follow-up was 4.60 ± 3.91 years.

Results

The mean age for childhood CD onset was 0.90 ± 0.61 years. An Avelino DNA test revealed a heterozygous R124L mutation. Clinical manifestations included recurrent photophobia, tearing, and a foreign body sensation. Recurrence frequency decreased with age. Slit lamp microscopy revealed a rough corneal epithelium. The anterior matrix under the corneal epithelium and the anterior elastic layer were scattered with gray and white opacity. From onset to follow-up, the children’s visual acuity decreased from 0.34 ± 0.12 to 0.55 ± 0.17 LogMAR units. AS-OCT showed uneven corneal epithelial thickness. The Bowman’s layer was replaced by abnormal substances in the anterior segment. Corneal deposits became increasingly thicker; the average thickness at the last follow-up was 102.78 ± 10.13 μm. IVCM revealed uneven and reflective signals in the corneal upper cortex and subepithelium, with unclear boundaries and a loss of normal cell morphology.

Conclusion

We report an early age of onset in a family with prevalent CD due to R124L mutations. AS-OCT is a convenient, quick, and non-contact tool for screening and monitoring the pathological process of CD.

[Clinical and morphological characteristics of corneal epithelial dystrophy (clinical observations)]

This paper presents clinical observations that can be regarded as degeneration of the basement membrane of the corneal epithelium. Difficulties in identifying such forms of corneal dystrophies, on the one hand, are associated with limitation and polymorphism of the clinical picture, and, on the other hand, with insufficient information content of the basic diagnostic methods (i.e. the methods used during the initial examination). The presented clinical cases allow singling out the alarming and pathognomonic signs of the disease in the diagnostic algorithm. In the first case, attention should be paid to biomicroscopic changes in the superficial layers of the cornea and the optical defects, which can be regarded as a manifestation of an irregularity of corneal refraction. Identification of pathognomonic signs of the disease is possible on the basis of a detailed, close-to-morphological study of the structure of superficial corneal layers using confocal microscopy and optical coherence tomography. At the same time, the localization of the detected changes at the level of epithelial basement membrane and its basal sections is of crucial significance for substantiating the diagnosis. In addition, according to the literature data, recurrent erosions of the cornea of unclear etiology should be attributed to presumptive signs of degenerative changes in the basement membrane of the epithelium.

Bilateral reticular haze and scar involving central cornea

A 17-year-old girl with a few years' history of declining vision, photophobia, and dry eye symptoms was referred to our clinic. She noted that the vision in the right eye declined significantly over the past several months. On her last year examination, her uncorrected distance visual acuity (UDVA) was recorded as 20/25 in both eyes with a corrected distance visual acuity (CDVA) of 20/20 in both eyes with minimal refractive error, with a diagnosis of bilateral Salzmann nodular degeneration. The patient was given artificial tears and was encouraged to wear sunglasses. On examination now, UDVA was 20/70 in the right eye and 20/40 in the left eye. The manifest refraction was -2.00 + 1.25 × 96 in the right eye and -1.00 + 2.00× 34 in the left eye, with a CDVA of 20/50 and 20/30, respectively. Slitlamp examination revealed superficial reticular stromal scar with clear intervening spaces involving the anterior 75 μm of the stromal cornea in the central 6.0 mm optical zone (Figure 1).JOURNAL/jcrs/04.03/02158034-202104000-00021/figure1/v/2021-04-19T183640Z/r/image-tiffJOURNAL/jcrs/04.03/02158034-202104000-00021/figure2/v/2021-04-19T183640Z/r/image-tiff The rest of the anterior and posterior segment examination was completely normal and noncontributory. Anterior segment optical coherence tomography (AS-OCT) revealed subepithelial lesion involving the central aspect of the cornea in the right eye more than that in the left eye (Figure 2). Family history was significant for an older sister with a similar problem who never required medical attention. She also has mild photophobia and dry eye symptoms. What is your differential diagnosis? What diagnostic test will help you in your diagnosis and clinical decision-making? What is the most likely diagnosis in this case? Do you recommend medical and/or surgical intervention in the right eye, realizing that there has been exacerbation of her ocular condition in the most recent year? What is the long-term prognosis and future plan for a patient with this potential condition?