Hydrogels in Ophthalmology: Novel Strategies for Overcoming Therapeutic Challenges

The human eye's intricate anatomical and physiological design necessitates tailored approaches for managing ocular diseases. Recent advancements in ophthalmology underscore the potential of hydrogels as a versatile therapeutic tool, owing to their biocompatibility, adaptability, and customizability. This review offers an exploration of hydrogel applications in ophthalmology over the past five years. Emphasis is placed on their role in optimized drug delivery for the posterior segment and advancements in intraocular lens technology. Hydrogels demonstrate the capacity for targeted, controlled, and sustained drug release in the posterior segment of the eye, potentially minimizing invasive interventions and enhancing patient outcomes. Furthermore, in intraocular lens domains, hydrogels showcase potential in post-operative drug delivery, disease sensing, and improved biocompatibility. However, while their promise is immense, most hydrogel-based studies remain preclinical, necessitating rigorous clinical evaluations. Patient-specific factors, potential complications, and the current nascent stage of research should inform their clinical application. In essence, the incorporation of hydrogels into ocular therapeutics represents a seminal convergence of material science and medicine, heralding advancements in patient-centric care within ophthalmology.

Retinal Prostheses: Engineering and Clinical Perspectives for Vision Restoration

A retinal prosthesis, also known as a bionic eye, is a device that can be implanted to partially restore vision in patients with retinal diseases that have resulted in the loss of photoreceptors (e.g., age-related macular degeneration and retinitis pigmentosa). Recently, there have been major breakthroughs in retinal prosthesis technology, with the creation of numerous types of implants, including epiretinal, subretinal, and suprachoroidal sensors. These devices can stimulate the remaining cells in the retina with electric signals to create a visual sensation. A literature review of the pre-clinical and clinical studies published between 2017 and 2023 is conducted. This narrative review delves into the retinal anatomy, physiology, pathology, and principles underlying electronic retinal prostheses. Engineering aspects are explored, including electrode-retina alignment, electrode size and material, charge density, resolution limits, spatial selectivity, and bidirectional closed-loop systems. This article also discusses clinical aspects, focusing on safety, adverse events, visual function, outcomes, and the importance of rehabilitation programs. Moreover, there is ongoing debate over whether implantable retinal devices still offer a promising approach for the treatment of retinal diseases, considering the recent emergence of cell-based and gene-based therapies as well as optogenetics. This review compares retinal prostheses with these alternative therapies, providing a balanced perspective on their advantages and limitations. The recent advancements in retinal prosthesis technology are also outlined, emphasizing progress in engineering and the outlook of retinal prostheses. While acknowledging the challenges and complexities of the technology, this article highlights the significant potential of retinal prostheses for vision restoration in individuals with retinal diseases and calls for continued research and development to refine and enhance their performance, ultimately improving patient outcomes and quality of life.

Retinitis Pigmentosa: Novel Therapeutic Targets and Drug Development

Retinitis pigmentosa (RP) is a heterogeneous group of hereditary diseases characterized by progressive degeneration of retinal photoreceptors leading to progressive visual decline. It is the most common type of inherited retinal dystrophy and has a high burden on both patients and society. This condition causes gradual loss of vision, with its typical manifestations including nyctalopia, concentric visual field loss, and ultimately bilateral central vision loss. It is one of the leading causes of visual disability and blindness in people under 60 years old and affects over 1.5 million people worldwide. There is currently no curative treatment for people with RP, and only a small group of patients with confirmed RPE65 mutations are eligible to receive the only gene therapy on the market: voretigene neparvovec. The current therapeutic armamentarium is limited to retinoids, vitamin A supplements, protection from sunlight, visual aids, and medical and surgical interventions to treat ophthalmic comorbidities, which only aim to slow down the progression of the disease. Considering such a limited therapeutic landscape, there is an urgent need for developing new and individualized therapeutic modalities targeting retinal degeneration. Although the heterogeneity of gene mutations involved in RP makes its target treatment development difficult, recent fundamental studies showed promising progress in elucidation of the photoreceptor degeneration mechanism. The discovery of novel molecule therapeutics that can selectively target specific receptors or specific pathways will serve as a solid foundation for advanced drug development. This article is a review of recent progress in novel treatment of RP focusing on preclinical stage fundamental research on molecular targets, which will serve as a starting point for advanced drug development. We will review the alterations in the molecular pathways involved in the development of RP, mainly those regarding endoplasmic reticulum (ER) stress and apoptotic pathways, maintenance of the redox balance, and genomic stability. We will then discuss the therapeutic approaches under development, such as gene and cell therapy, as well as the recent literature identifying novel potential drug targets for RP.

PARACENTRAL ACUTE MIDDLE MACULOPATHY ASSOCIATED WITH IDIOPATHIC INTRACRANIAL HYPERTENSION

PURPOSE

Paracentral acute middle maculopathy (PAMM) is a recently identified clinical entity with numerous retinal vascular and systemic associations. To our knowledge, this is the first reported case of PAMM associated with idiopathic intracranial hypertension.

METHODS

A case is presented with multimodal imaging.

RESULTS

A patient with idiopathic intracranial hypertension is found to have the characteristic clinical, spectral domain optical coherence tomography, and OCT angiography findings associated with PAMM.

CONCLUSION

Paracentral acute middle maculopathy is believed to arise from a microvascular insult to the retinal deep capillary plexus. We add a previously undescribed association with idiopathic intracranial hypertension to the list of etiologies that can cause PAMM.

NOVEL APPROACH TO SCLERAL FIXATION OF A REPER INTRAOCULAR LENS AND ARTIFICIAL IRIS COMPLEX FOLLOWING PARS PLANA LENSECTOMY AND VITRECTOMY FOR ECTOPIA LENTIS AND CATARACT IN A PATIENT WITH ANIRIDIA AND NYSTAGMUS

PURPOSE

Prosthetic iris devices have recently been used to improve cosmesis and reduce glare in aniridia. There is currently no consensus on which prosthetic iris device or which surgical approach is preferred for managing large iris defects.

METHODS

A novel surgical approach with Gore-Tex polytetrafluoroethylene sutures was used to achieve scleral fixation of an intraocular lens and artificial iris complex in a 19-year-old Caucasian female patient with aniridia, nystagmus, cataracts, and ectopia lentis.

RESULTS

Six weeks postoperatively, the intraocular lens-artificial iris complex remained well centered, and the vision in the left eye improved from 20/400 to 20/70. Two years after prosthetic iris device implantation, there have been no complications.

CONCLUSION

This case demonstrates a promising proof-of-concept for long-term management of complicated aniridia cases using an intraocular lens and artificial iris complex prosthetic iris devices. Gore-Tex sutures may be preferable to conventional polypropylene sutures because of their improved durability.

Refractive, visual, and subjective quality of vision outcomes for very high myopia LASIK from - 10.00 to - 13.50 diopters

Background

To evaluate laser-assisted in situ keratomileusis (LASIK) outcomes, subjective quality of vision (QoV) and patient satisfaction in eyes with very high myopia (VHM) above − 10.00 diopters (D).

Methods

Consecutive myopic and myopic-astigmatism eyes with spherical equivalent (SEQ) ranging between − 10.00 to − 13.50 D underwent LASIK with the WaveLight® Allegretto Wave® Eye-Q 400 Hz excimer laser. Treatment accuracy, efficacy, safety, stability, cylinder vectors, and higher-order aberrations were evaluated, together with subjective QoV and night vision disturbances (NVDs).

Results

114 eyes had a preoperative SEQ of − 11.02 ± 0.81 D, with a median follow-up of 24 months. A total of 72, 84, and 94% of eyes were within ± 0.50, ± 0.75 and ± 1.00 D of intended SEQ (R² = 0.71). The efficacy index was 0.93 ± 0.20, with 51 and 81% of eyes achieving 20/20 and 20/25. The astigmatism correction index was 0.95 ± 0.33. The safety index was 1.05 ± 0.12. The average myopic regression was − 0.51 ± 0.38 D. Preoperative QoV scores improved significantly postoperatively (7.5 ± 0.8 vs. 9.1 ± 0.7; P <  0.001), with less NVDs (P <  0.001). Total, spherical and coma root mean square (RMS) postoperative ocular higher-order aberrations were 1.07 ± 0.34, 0.67 ± 0.25, and 0.70 ± 0.40 μm.

Conclusions

Very high myopia LASIK between − 10.00 to − 13.50 D is safe and results in good visual outcomes, with high patient satisfaction and a significant improvement in patient-reported QoV after surgery. Appropriately selected patients within this very high myopia group can be included as LASIK candidates.

OPACIFICATION OF SCLERAL-SUTURED AKREOS AO60 INTRAOCULAR LENS AFTER VITRECTOMY WITH GAS TAMPONADE: CASE SERIES

BACKGROUND/PURPOSE

We report the first two cases of postoperative opacification of scleral-sutured Akreos AO60 intraocular lens after vitrectomy with the gas tamponade.

METHODS

Two patients with ectopia lentis underwent pars plana vitrectomy, pars plana lensectomy, and scleral fixation of an Akreos AO60 intraocular lens with Gore-Tex suture. Retinal breaks were noted during vitrectomy and consequently intravitreal gas tamponade was used after endolaser retinopexy. Postoperatively, both patients developed intraocular lens opacification but maintained excellent visual acuity; however, one patient developed bothersome though tolerable photophobia.

CONCLUSION

Although still an excellent option for the management of surgical aphakia in the absence of capsular support, caution should be taken when using a hydrophilic secondary intraocular lens, such as Akreos AO60, during vitreoretinal surgery if gas is required.

Neovascularization of the iris in retinoschisis

Purpose

To report the association of rubeosis iridis with chronic bullous degenerative peripheral retinoschisis.

Observations

A 63-year-old female presented with acute hyphema and neovascularization of the iris in association with elevated intraocular pressure. Posterior segment examination including imaging revealed no vascular occlusion as a potential cause. However, large, peripheral bullous retinoschisis was noted in the right eye. No nonperfusion aside from that seen within the schism detachment, or neovascularization of the retina on wide-field fundus photography or fluorescein angiography was noted. Bullous retinoschisis was also found in the left eye. The patient was treated conservatively with prednisolone acetate and timolol eye drops.

Conclusions and importance

Chronic bullous retinoschisis can be associated with anterior segment neovascularization such as rubeosis iridis, presumably due to non-perfusion within the retinoschisis cavity.

Optical coherence tomography angiography of diffuse unilateral subacute neuroretinitis

Purpose

Diffuse unilateral subacute neuroretinitis (DUSN) is often a challenging diagnosis to make. We present a DUSN case with its multimodal imaging to aid in the diagnosis, emphasizing the observations on optical coherence tomography angiography (OCTA).

Observations

The evolution of a DUSN case is presented. Fundus photography and OCTA aided in the identification of the nematode.

Conclusions and importance

DUSN is a difficult diagnosis to establish. We report the first case to our knowledge in which OCTA aided in the diagnosis of DUSN.

En Face Optical Coherence Tomography Analysis to Assess the Spectrum of Perivenular Ischemia and Paracentral Acute Middle Maculopathy in Retinal Vein Occlusion

PURPOSE

To assess the spectrum of perivenular ischemia in eyes with retinal vascular obstruction (typically central or hemicentral retinal vein obstruction) using en face optical coherence tomography (OCT).

DESIGN

Retrospective observational case series.

METHODS

Eyes with recent retinal vascular occlusion illustrating paracentral acute middle maculopathy (PAMM) in a perivenular fern-like pattern with en face OCT were evaluated in this study. Multimodal retinal imaging including en face OCT segmentation of the inner nuclear layer was performed in all patients. Color fundus photography and fluorescein angiography (FA) images were used to create a vascular overlay of the retinal veins vs the retinal arteries to map the distribution of PAMM with en face OCT analysis.

RESULTS

Multimodal retinal imaging was performed in 11 eyes with acute retinal vascular obstruction. While 7 eyes demonstrated obvious findings of retinal vein obstruction (5 with central and 2 with hemicentral retinal vein occlusion), 4 eyes were unremarkable at presentation. En face OCT analysis demonstrated a spectrum of perivenular PAMM illustrating a fern-like pattern with sparing of the periarteriolar area in all cases.

CONCLUSION

En face OCT may illustrate a remarkable perivenular pattern of PAMM in eyes with retinal vascular obstruction even in the absence of significant funduscopic findings. Perivenular PAMM with en face OCT demonstrates a wide spectrum of variation with narrow fern-like perivenular lesions at the mildest end and more diffuse lesions with only periarterial sparing at the most severe end of the spectrum. Arterial hypoperfusion secondary to outflow obstruction from a central retinal vein obstruction appears to be the most common cause of this presentation, although primary arterial hypoperfusion may also be an etiology.

RETINAL ARTERIOVENOUS MALFORMATION

PURPOSE

To describe a case of an isolated Group 3 retinal arteriovenous malformation (AVM).

METHODS

Observational case report.

RESULTS

A 15-year-old girl with no significant medical history presented with no light perception vision in her right eye and gradually decreasing vision in her left eye over several years. She was found to have a large AVM in the posterior pole of the right eye with associated perivascular sheathing in the periphery. Her left eye seemed totally unremarkable. Neuroimaging revealed no intracranial or intraorbital abnormalities. A diagnosis of isolated Group 3 retinal AVM was made.

CONCLUSION

Retinal AVMs are congenital, nonhereditary, and sporadic vascular anomalies that develop in the posterior pole. A number of patients with this finding can have coexisting AVMs in the brain, mandible, skin, or orbit, which comprises the Wyburn-Mason syndrome. Because of these systemic associations, neuroimaging should always be considered when a retinal AVM is seen. Severe vision loss can occur from these AVMs secondary to a number of ocular complications, including central retinal vein occlusions.

ACUTE MACULAR NEURORETINOPATHY WITHOUT NEAR-INFRARED REFLECTANCE-AN ATYPICAL CASE PRESENTATION

BACKGROUND

Acute macular neuroretinopathy is a rare disease that with the help of multimodal imaging is being diagnosed more frequently.

METHODS

An atypical case is presented and followed by multimodal imaging.

RESULTS

A typical acute macular neuroretinopathy lesion was seen on biomicroscopic examination and spectral domain optical coherence tomography examination. However, near-infrared imaging revealed a lack of the characteristic finding along with a relative afferent pupillary defect and a widespread depressed multifocal electroretinogram which has not been reported previously.

CONCLUSION

This patient exhibits photoreceptor and outer retinal findings commonly described in acute macular neuroretinopathy lesion without classic near-infrared findings. This case may represent a severe form of acute macular neuroretinopathy.