Ophthalmic Gene Therapy Subretinal Injection

Sisk, Robert A.

December 07, 2022

Ophthalmic Gene Therapy Subretinal Injection

Intraoperative OCT-assisted leber congenital amaurosis (LCA) macular repair

Diffuse retinal degeneration with relative macular sparing. Typical_diffuse_retinal_degeneration_with_relative_macular_sparing.jpg

About the case study

Leber congenital amaurosis (LCA) is a group of congenital retinal dystrophies, which can lead to severe vision loss at an early age. Patients usually present with nystagmus, sluggish or near-absent pupillary responses, severely decreased visual acuity, photophobia and high hyperopia [1]. Ophthalmic gene therapy can provide significant vision improvement for these patients [2]. The genes are delivered through an AAV vector injected subretinally during surgery.

Subretinal ophthalmic gene therapy injection requires high levels of precision. As such, intraoperative Optical Coherence Tomography (OCT) is an essential tool. It provides ophthalmic surgeons with real-time information during surgery, supporting bleb management and allowing confirmation that the desired volume of vector reached the subretinal space. Intraoperative OCT can also help prevent complications such as the formation of an intraoperative macular hole during vector injection.

What to expect in the case study

Key Learnings

Learn about the surgical management of a 21-year-old patient with retinal degeneration and type 2 Leber congenital amaurosis (LCA)
Discover the different steps of subretinal ophthalmic gene therapy injection
Understand the role of intraoperative OCT in a macular repair procedure

Ophthalmic gene therapy case description

A 21-year-old Hispanic female had poor vision from birth including nyctalopia, visual field constriction, reduced visual acuity and reduced color perception. She noticed slowly progressive functional decline. Although she completed high school, she had worsening navigation and was challenged to live and work independently due to her visual limitations.

Figure 1: Caption: The macular OCT and ultra-wide field fundus images showed baseline pigmentary retinopathy and photoreceptor alterations relatively sparing the fovea. Images provided by Robert A. Sisk, MD, FACS.

Diagnosis & pre-operative assessment

Pre-operative visual acuity was 20/150 in both eyes. The patient exhibited typical diffuse retinal degeneration with relative macular sparing. Genetic testing revealed biallelic RPE65 variants causing retinal degeneration and indicating type 2 Leber congenital amaurosis. Based upon the presence of viable retinal cells and potential benefit from ophthalmic gene therapy, treatment was offered by subretinal injection for both eyes. Surgeries were performed two weeks apart. The macular OCT and ultra-wide field fundus images showed baseline pigmentary retinopathy and photoreceptor alterations relatively sparing the fovea.

Macular scan performed to document the pre-injection anatomy. Images provided by Robert A. Sisk, MD, FACS . — Figure 2: Macular scan performed to document the pre-injection anatomy. Images provided by Robert A. Sisk, MD, FACS.

Download case study: Ophthalmic Gene Therapy Subretinal Injection (pdf)

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