Wound leaks
Small wound leaks with a well-formed anterior chamber can be conservatively managed with patching or a large diameter bandage contact lens with prophylactic topical antibiotics. Topical aqueous suppressants could be considered to decrease flow through the leak, but risk exacerbating the low eye pressure.
Cyanoacrylate may be applied over a focal leak with a contact lens placed over the glue for comfort and stability.
Larger wound leaks that cause clinically significant hypotony or seem unlikely to spontaneously resolve are best managed with surgical revision.
Cyclodialysis cleft
Separation of the ciliary body from the scleral spur creates a large direct channel for uveoscleral outflow. Detachment of the ciliary body may, but does not necessarily, reduce aqueous humor production.
Cleft size does not bear directly on the degree of hypotony. [20] The cleft may have been inadvertently created during ocular surgery or following trauma, or intentionally created during a glaucoma operation.
A cyclodialysis cleft may be identified gonioscopically, by anterior segment imaging, or during exploratory surgery. Gonioscopy can be difficult on a soft globe.
Treatment options include argon laser photocoagulation, cryotherapy, external diathermy, ciliary body suturing, and vitrectomy with endotamponade. [21]
Clefts can spontaneously close and result in a dramatic rise in IOP.
Miotics should be avoided to prevent recurrence of cleft opening. After cleft closure, long-term cycloplegia may be indicated.
Retinal detachment
Rhegmatogenous retinal detachment usually is associated with mild hypotony. Occasionally, with large detachments or proliferative vitreoretinopathy, profound hypotony may develop.
In rhegmatogenous detachments, the mechanism is believed to be the egress of aqueous humor through the vitreous, the retinal hole, and across the retinal pigment epithelium. Concurrent iridocycl*tis may also reduce aqueous humor production.
Hypotony may resolve slowly following repair of the detachment because of lingering inflammation, or it may quickly reverse if, for example, a scleral buckle or silicone oil is used.
Overfiltering bleb or tube shunt, or posttraumatic hypotony
Acute
Mild transient hypotony following glaucoma surgery is common and usually well tolerated.
Observe and treat with liberal anti-inflammatory agents, cycloplegic agents, and reformation of the anterior chamber with viscoelastic, if needed. Viscoelastic injections may be given repeatedly.
Continue topical antibiotics for several days beyond the last chamber reformation procedure.
Anterior chamber shallowing becomes clinically significant if corneal-iris touch or corneal-lens touch results in development of synechiae or corneal decompensation.
Consider draining large choroidal effusions if no sign of improvement is present after several (7-14) days of medical and/or chamber reformation management, especially if retinal apposition is noted, the anterior chamber is markedly shallow, or the patient is at higher risk for hemorrhage. Hemorrhage risk factors include advanced age, history of glaucoma, history of vascular disease, and anticoagulated status. Even large choroidal effusions can resolve with conservative management, avoiding the need for further surgery.
Chronic
Surgical wound revision with resuturing of the scleral flap and/or conjunctival advancement or autograft is the procedure of choice for incompetent or overfiltering trabeculectomy. [22] Blood patch, laser application, cautery, cryotherapy, and trichloroacetic acid may work in some instances but are less effective. Conjunctival compression sutures work well to flatten a large bleb causing dysesthesia and also can help resolve hypotony. [23] Case reports have described some success with intracameral platelet-rich plasma injection. [24] Case series also have shown success with the use of collagen cross-linking for the treatment of leaking custic blebs. [25]
Conjunctival flaps alone can work well for diffusely incompetent blebs due to tissue thinning and avascularity.
Focal leaks may be treated with cyanoacrylate and a bandage lens, or temporary patching.
In a series of patients with chronic hypotony due to overfiltering blebs, 68% of cases resolved within 6 months of a subsequent cataract surgery. [26]
In cases of persistent hypotony in the setting of glaucoma drainage devices, several potential surgical management techniques have been reported including suture ligation of the tube, [27] ab interno-stent implantation in the lumen, [28] or externalization of the tube from the chamber.
Eroded tube shunts can be particularly challenging to stabilize, and numerous graft alternatives, including cornea, dermis, and fascia lata, have been used with some success. [29] Care must be taken to remove any epithelial tissue that has grown in through the erosion. The tube should be redirected, if possible. In most cases of recurrent tube erosion, the device should be removed.
Laser trabecular sclerosis can be considered for severe, chronic hypotony if the cornea is adequately clear. [30] Long-term silicone oil fill is an option for those with cloudy corneas and can be combined with implantation of a keratoprosthesis. [31] Repeated intracameral injections of highly reticulated hyaluronic acid have provided stability in some cases. [16] Improved hypotony after placing a capsular tension ring in the angle has been reported. [32]
Uveitis
Anti-inflammatory agents are the mainstay of treatment. Peribulbar or intravitreal steroid injections have been used with some success, even in pre phthisical eyes. Surgical removal of a cycl*tic membrane may release tractional detachment of the ciliary body.
Vitrectomy and placement of silicone oil may be useful in refractory cases. [33]
