A novel method for retinal detachment repair – A/Prof Wilson Heriot

By A/Prof Wilson Heriot

Retinal detachments (RD) cause blindness when fluid flows through a tear or hole like a tyre deflating from a puncture. The most common repair method nowadays is to remove the intraocular vitreous gel, reposition the retina and fill the cavity with supportive gas or oil while the laser “spot welding” of the tear matures.

Revisiting the basic principles of tissue repair led to the concept that the tear could be fused to the underlying tissue by eliminating the fluid separating them before laser photocoagulation, a method called retinal thermofusion (RTF).¹

Intraocular gas prohibits aeromedical evacuation of injured personnel and prompted the US Army Medical Research and Materiel Command to prioritise the development of a method for RD repair independent of gas tamponade.

Based on the RTF concepts, a collaborative team at the Centre for Eye Research Australia (CERA) and the Department of Optometry and Vision Science at the University of Melbourne (UniMelb) secured those funds and developed a novel method and device. We have now secured additional funding to facilitate translation of the RTF method into clinical care.

In terms of vitreoretinal surgery, how big of an impact could this new approach have?

For over a century, RD repair has been based on the principles established by Jules Gonin,^2,3 which involves thermally injuring the retinal tear(s) and underlying tissues and bringing them into contact. Tissue injury creates a “glue” but for wound healing to create a seal, both tissues must be held in contact for weeks.

Intraocular gas blurs vision and a liquid (usually silicone oil) requires additional surgery to remove it. The current methods not only delay return to normal activities, prohibit air travel, and sometimes necessitate additional surgery, but can also have a negative impact on the quality of vision. Draining subretinal fluid to create space for the gas or oil is increasingly being recognised as causing worse visual acuity, more distortion, retinal fold formation or even macular displacement.^4,5

The ideal method for RD repair should eliminate the cause – the retinal tear – and allow the retina to re-attach itself by physiological mechanisms, including retinal pigment epithelial (RPE) pumping and the oncotic gradient between the vitreous and choroid.^6-8

The CERA-UniMelb collaborative team have achieved exactly this by utilising the physical properties of water which absorbs and is energised by near infrared light with peaks at 1490 nm and 1940 nm. Thus, dehydration of the subretinal space around the tear is achieved by the laser aided by a coaxial low flow air stream to displace liberated water molecules. With the retina and RPE in contact, photocoagulation seals the tear intraoperatively. The retina can reattach itself physiologically. In their most recent paper, using an in vivo RD model, the team shows that the RTF approach achieved stable retinal reattachment.⁸

An important feature of this water absorbing wavelength is that it initially treats the tear margin at low power evaporating the subretinal fluid and then photocoagulating it at a higher power. Thus, the seal can be created with one device and it is an intuitive method for surgeons already trained to laser retinal tears. The additional time for the dehydration is offset by the elimination of the steps introducing the gas.

The RTF approach being independent of tamponade has the potential for better visual outcomes, a faster return to normal activities for most patients, and should eliminate the need for a second procedure for liquid tamponade removal in those with more complex problems.

In terms of next steps, the funding for translation of this method to clinical care includes the development of a pre- commercial laser/air stream console and a preclinical trial recruiting 10 patients with “macula off” rhegmatogenous retinal detachment from the Royal Victorian Eye and Ear Hospital (East Melbourne, Victoria) in early 2023. Should the retinal thermofusion technique prove beneficial in a clinical trial, it should be a significant step forward in patient care.

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References

1. Heriot W. Thermofusion of the retina with the RPE to seal tears during retinal detachment repair. Graefe’s Archives for Clinical & Experimental Ophthalmology 2016;254(4):691-96. doi: 10.1007/s00417-016-3295-0
2. Rumpf J. Jules Gonin. Inventor of the surgical treatment for retinal detachment. Survey of Ophthalmology 1976;21(3):276-84.
3. Wolfensberger T. Jules gonin. Pioneer of retinal detachment surgery. Indian Journal of Ophthalmology 2003;51(4):303-08.
4. Brosh K, Francisconi CLM, Qian J, et al. Retinal Displacement Following Pneumatic Retinopexy vs Pars Plana Vitrectomy for Rhegmatogenous Retinal Detachment. JAMA Ophthalmology 2020 doi: 10.1001/jamaophthalmol.2020.1046
5. Hillier RJ, Felfeli T, Berger AR, et al. The Pneumatic Retinopexy versus Vitrectomy for the Management of Primary Rhegmatogenous Retinal Detachment Outcomes Randomized Trial (PIVOT). Ophthalmology 2019;126(4):531-39. doi: https://doi.org/10.1016/j.ophtha.2018.11.014
6. Bill A, Phillips CI. Uveoscleral drainage of aqueous humour in human eyes. Exp Eye Res 1971;12(3):275-81. [published Online First: 1971/11/01]
7. Marmor MF. Control of subretinal fluid: Experimental and clinical studies. Eye 1990;4(2):340-44. doi: 10.1038/eye.1990.46
8. Heriot WJ, Metha AB, He Z, et al. Optimizing retinal thermofusion in retinal detachment repair: achieving instant adhesion without air tamponade. Ophthalmology Science 2022:100179.

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