Are You Aware of the Port Delivery System?

Garbita Chatterjee, Optometry Student

Intern optometrist, Dr. Shroff’s Charity Eye Hospital, Delhi, India

Age-related macular degeneration (ARMD) is a senile macular degeneration, a bilateral disease that occurs in persons over 50 years of age. It is the leading cause of blindness in developed countries.⁽¹⁾ Neovascular AMD impacts approximately 20 million people worldwide. ⁽²⁾

Currently used treatment modalities for ARMD patients:

Dry ARMD

• Vitamin & antioxidants supplementation
• Nutritional changes along with lifestyle changes

Wet ARMD

• Intravitreal anti VEGF therapy
• Photodynamic therapy (PDT)
• Transpupillary therapy (TTT)
• Double frequency YAG 532 nm photocoagulation
• Low vision aids & surgical treatment

The upcoming advancement in the treatment includes the Port Delivery System (PDS). It is named SUSVIMO. ⁽²⁾ Susvimo (ranibizumab injection) 100mg/ml for intravitreal use via ocular implant is for the treatment of people with neovascular or wet age-related macular degeneration who have previously responded to at least two anti-vascular endothelial growth factors (VEGF). ⁽³⁾ Ranibizumab is a vascular endothelial growth factor (VEGF) inhibitor designed to bind to and inhibit VEGF-A, a protein that has been shown to play a critical role in the formation of new blood vessels and the leakiness of vessels. ⁽²⁾ The PDS is designed to be a permanent, reusable drug reservoir. It is initially surgically placed in the sclera, and subsequent filling is done. ⁽²⁾

The device is made of polysulfone. It includes a silicone septum that can be entered with a special needle for refill. During the refill, the needle flushes out of the device while at the same time refilling it with fresh ranibizumab. ⁽²⁾ At the distal end of the septum, there is a semipermeable titanium membrane that permits continuous passive diffusion of the drug from the higher concentration in the reservoir into the vitreous. It is approved by the Food and Drug Administration. Refill is done every 6 months (about 24 weeks). This is an FDA-approved treatment. ⁽²⁾ A ladder study was done which included 220 patients, and among which a correlation was noted between dose concentration and median time to refill, noting that roughly 80% were able to go at least 6 months before needing their first refill. ⁽³⁾ In the archway study, Susvimo was generally well-tolerated, with a favourable benefit-risk profile. The study was a randomised one, evaluating the efficacy and safety of Susvimo. ⁽³⁾ Susvimo is different from ranibizumab intravitreal injections, a medicine marketed as Lucentis, which is approved to treat neovascular or wet age-related macular degeneration. ^(2-5)

Optometrists are the primary eye care providers and the forefront who help in early diagnosis, providing proper suggestions about the management, and can save the sight of people from severe vision loss diseases like AMD. For optometrists, knowing about proper management is very much necessary so that they can make the patients aware of the stages of AMD and let them consult with a retina specialist for urgent interventions. With every new treatment modality, the approach to dealing with changes, because of which an optometrist should always be updated about them and counsel their patients accordingly, through initial diagnosis & later-stage counselling through rehabilitation. This is currently being used in western countries in a broad manner and soon will be approaching in the nation to serve and save thousands of sights.

References:

1. Khurana AK. Comprehensive ophthalmology 8^TH edition. Jaypee brothers medical publishers.
2. Pennington KL, DeAngelis MM.2016.Epidemiology of age-related macular degeneration (AMD): associations with cardiovascular disease phenotypes and lipid factors. Eye and Vision.
3. Campochiaro PA, Marcus DM, Awh CC, et al. April 1, 2019]. The port delivery system with ranibizumab for neovascular age-related macular degeneration: results from the randomized phase 2 LADDER clinical trial [published online ahead,Ophthalmology
4. Holz FG, Tadayoni R, Beatty S, et al.2015.  Multi-country real-life experience of anti-vascular endothelial growth factor therapy for wet age-related macular degeneration. Br J Ophthalmol.
5. Rao P, Lum F, Wood K, et al. 2018. Real-world vision in age-related macular degeneration patients treated with single anti-VEGF drug type for 1 year in the IRIS registry. Ophthalmology