Deep Sclerectomy With Scleral Bed Fenestration Versus Trabeculectomy in Medically Uncontrolled Primary Open Angle Glaucoma Patients

Glaucoma is an optic neuropathy that is characterized by progressive structural and functional deterioration of the optic nerve (1) Glaucoma is the second leading cause of blindness worldwide, although it is the most common cause of irreversible vision loss in the whole world (2) In 2013, the number of people (aged 40-80 years) diagnosed with glaucoma worldwide was 64.3 million, increasing to 76.0 million in 2020 and expected to reach 111.8 million in 2040 (2) Primary open angle glaucoma is the commonest subtype of glaucoma. The number of persons diagnosed with POAG was estimated 52.68 million in 2020 and expected to be 79.76 million in 2040 (3).

In primary open angle glaucoma vision preservation remains the aim of treatment through correcting the only treatable risk factor in glaucoma which is the intraocular pressure. This can be achieved by different modalities including medical, laser or surgical methods (4)

In many cases medical and laser therapy can provide an effective IOP control, while surgery is still indicated when they fail to lower IOP sufficiently, or if the patient is not compliant to those methods of treatment (5).

Surgeries done for treatment of POAG are variable, including penetrating surgeries & non penetrating surgeries (6)

The example of penetrating surgeries is the trabeculectomy (both conventional or with modifications as application of mitomycin) &while examples of non-penetrating surgeries are multiple as deep sclerectomy, canaloplasty, gonioscopy-assisted transluminal trabeculotomy , goniotomy with kahook dual blade, or I stent implantation(7).

Trabeculectomy is a filtration procedure that reduces IOP by creating a connection between the anterior chamber & the subconjunctival space after excision of a part of the trabecular meshwork. Unfortunately, although it reduces IOP effectively it is associated with a higher incidence of complications as hypotony, lost anterior chamber or suprachoroidal effusion (8).

Therefore, non-penetrating glaucoma surgeries as deep sclerectomy have been developed to improve the safety of the conventional filtering procedures(9).

Deep sclerectomy prevents the sudden hypotony that occurs in penetrating surgeries by creating progressive filtration of aqueous humor without perforating the eye through the preservation of the thin trabeculo-Descemet membrane (5) Nevertheless, many authors think that deep sclerectomy is less effective than trabeculectomy for intraocular pressure reduction ,hence adding a new modification to deep sclerectomy is needed to increase its efficacy (10)