Chronic ocular hypotony remains one of the most difficult problems in ophthalmic care. Defined by persistently low intraocular pressure accompanied by structural changes to the eye, this condition can quietly but relentlessly erode vision. For many patients, available treatments address only the underlying cause and not the downstream anatomical damage. A recent pilot study published in the British Journal of Ophthalmology introduces a structured, protocol driven approach that aims to restore ocular anatomy and visual function using intravitreal hydroxypropylmethylcellulose. While early and exploratory, the findings suggest a potentially meaningful advance for carefully selected patients.
Ocular hypotony is most commonly described as an intraocular pressure below normal physiological levels. Although there is no universal numerical definition, many clinicians consider pressures below 6.5 mm Hg to be clinically significant, particularly when associated with anatomical sequelae. Chronic hypotony is not simply a low pressure reading. Over time, inadequate intraocular pressure leads to deformation of the globe, retinal and choroidal changes, and ultimately irreversible vision loss.
Structural hypotony refers to this combination of low pressure and anatomical damage. Reported features include corneal edema and striae, shallow anterior chamber, lens instability, choroidal folds, optic disc swelling, hypotony maculopathy, reduced axial length, retinal pigment epithelial changes, and in advanced cases, phthisis bulbi. Once these changes are established, visual outcomes are often poor even if the underlying cause of hypotony is later corrected.
The causes of chronic hypotony are diverse. Excessive aqueous outflow following glaucoma surgery, cyclodialysis clefts, chronic inflammation affecting the ciliary body, and complex vitreoretinal disease are all well recognized contributors. Management typically focuses on addressing these root causes through medical or surgical means. Unfortunately, in many patients the ciliary body fails to recover adequate function, leaving the eye structurally compromised despite best efforts.
Historically, intravitreal or intracameral viscoelastic agents have been used sporadically to manage hypotony. These reports, dating back several decades, suggest that viscoelastics can temporarily increase intraocular pressure and support globe integrity. However, prior use has largely been anecdotal, without standardized protocols, consistent endpoints, or prospective follow up. As a result, there has been no established standard of care for restoring ocular anatomy in eyes with chronic hypotony and retained visual potential.
The recently published STRETCH pilot series attempts to address this gap. Conducted within a dedicated hypotony service at Moorfields Eye Hospital, the study evaluates intravitreal hydroxypropylmethylcellulose, or HPMC, delivered according to a structured treatment algorithm.
HPMC is a non ionic, cellulose based dispersive viscoelastic commonly used in cataract surgery to protect the corneal endothelium and maintain space within the anterior chamber. Its rheological properties make it distinct from cohesive sodium hyaluronate products. HPMC disperses evenly within the vitreous cavity, has a refractive index close to that of native vitreous, and provides moderate viscosity without forming dense pockets.
In the context of hypotony, these characteristics are appealing. By distributing uniformly, HPMC can offer diffuse structural support to the globe, counteracting scleral collapse and allowing intraocular pressure to rise. Its biocompatibility and gradual resorption profile further support its off label use in this setting, although inflammatory opacification remains a known risk.
The STRETCH study was designed as a prospective interventional case series. Eight eyes from seven patients with chronic structural hypotony were enrolled. All patients had experienced hypotony for more than three months, or more than six months following glaucoma filtration surgery, and had intraocular pressures below 6.5 mm Hg. Importantly, only eyes with demonstrable visual potential and a clear visual axis were included.
Patients with reversible causes of hypotony were excluded until those causes were addressed. Over draining glaucoma surgery, chronic retinal detachment, or active inflammation were managed first by the appropriate subspecialty teams. HPMC was used only as an adjunctive strategy once hypotony persisted despite correction of the primary pathology.
Visual potential was assessed rigorously using electrophysiological testing, including flash visual evoked potentials and full field electroretinography. This step was critical, as the intervention aims to preserve or restore function in eyes capable of visual recovery, rather than prolonging treatment in eyes without realistic potential.
Intravitreal injections of HPMC were administered every two to four weeks. Injection volumes varied between patients and visits, ranging from 70 to 1400 microliters, and were titrated to achieve predefined anatomical and pressure targets. Treatment continued until one of several endpoints was reached: restoration of premorbid axial length, sustained intraocular pressure between 10 and 15 mm Hg for four weeks without signs of hypotony, or axial length symmetry with the fellow eye.
Patients were followed for twelve months from the first injection. At each visit, best corrected visual acuity, intraocular pressure, axial length, and multimodal imaging findings were recorded. This structured approach distinguishes the study from earlier anecdotal reports.
Visual acuity improved in seven of eight treated eyes. Median best corrected visual acuity improved from 1.15 LogMAR at baseline to 0.4 LogMAR at twelve months. Gains ranged from one to nine lines, highlighting meaningful functional improvement for most patients.
Intraocular pressure increased in seven of eight eyes, with median pressure rising from 3.5 mm Hg to 9 mm Hg at one year. Although not all eyes reached normal pressure levels, even modest increases were associated with anatomical stabilization and visual benefit.
Axial length increased in six of eight eyes, with a median gain of 1 mm. This finding is particularly notable, as axial shortening is a hallmark of advanced hypotony and is rarely reversed. Central macular thickness also decreased in most eyes, consistent with improvement in hypotony maculopathy.
Adverse events were limited but instructive. Two eyes experienced inflammatory flare ups that led to temporary loss of HPMC clarity. These episodes were managed successfully with topical and intravitreal corticosteroids. Two additional eyes experienced transient vision loss immediately after injection, which resolved following paracentesis to reduce pressure.
These events underscore the need for careful patient selection, close monitoring, and readiness to manage pressure spikes or inflammatory responses. They also highlight that this therapy is not benign and should remain within specialist settings.
The authors emphasize that intravitreal HPMC is not a replacement for treating the underlying cause of hypotony. Rather, it is a tool to restore or preserve ocular anatomy once reversible factors have been addressed. In this sense, the therapy functions as a bridge, stabilizing the eye and preventing progression toward irreversible damage such as phthisis.
Compared with prior reports using various viscoelastic agents, the outcomes in this series are comparable or favorable. The combination of visual improvement, pressure elevation, and axial length restoration supports the value of a protocol driven approach rather than ad hoc intervention.
As a pilot series, the study has clear limitations. The sample size is small, and there is no control group. Natural fluctuations in hypotony and spontaneous improvement cannot be fully excluded. Longer follow up is also required to determine whether benefits are sustained and whether late complications emerge.
Despite these limitations, the study provides a foundation for future controlled trials. It also raises important questions about optimal viscoelastic choice, injection frequency, and objective endpoints for treatment success. Advances in ocular imaging and volume measurement may eventually allow more precise tailoring of therapy.
Chronic structural hypotony is under recognized and under reported, yet its consequences are profound. For patients with visual potential, the lack of effective restorative treatments has long been a source of frustration. This structured use of intravitreal HPMC offers a glimpse of a new therapeutic pathway, one that focuses not only on pressure numbers but on restoring the physical integrity of the eye.
While broader adoption awaits further evidence, the STRETCH study represents an important step forward. It reframes hypotony management as an active process of ocular rehabilitation rather than passive observation once primary treatments fail.
Intravitreal hydroxypropylmethylcellulose, delivered within a structured protocol, shows promise as a therapeutic option for selected patients with chronic structural ocular hypotony. Improvements in visual acuity, intraocular pressure, and axial length suggest that meaningful anatomical and functional recovery is possible even in long standing disease. Continued research will determine whether this approach can evolve into a standardized component of hypotony care.
Dias KOM, Yang E, Calcagni A, et al. Novel therapeutic strategies to restore vision in ocular hypotony (STRETCH): results from a prospective pilot series. British Journal of Ophthalmology. 2025. doi:10.1136/bjo-2025-327866.
Wang Q, Thau A, Levin AV, et al. Ocular hypotony: a comprehensive review. Survey of Ophthalmology. 2019;64:619 to 638.
Küçükerdönmez C, Beutel J, Bartz-Schmidt KU, et al. Treatment of chronic ocular hypotony with intraocular application of sodium hyaluronate. British Journal of Ophthalmology. 2009;93:235 to 239.
This blog is intended for informational and educational purposes only. It does not constitute medical advice and should not be used as a substitute for professional diagnosis or treatment. Clinical decisions should be made by qualified healthcare professionals based on individual patient circumstances, current guidelines, and full review of the original peer reviewed literature. The author has no financial relationship with the manufacturers of the products discussed.
