PST/Laser v. Laser Alone for CSME

Clinically significant macular edema (CSME) is one of the leading causes of vision loss in
diabetic retinopathy. The current standard of care for CSME is focal/grid laser
photocoagulation. However, many patients experience further vision loss and/or require
multiple laser treatments. In recent studies, intraocular (intravitreal) injection of
triamcinolone acetonide has been shown to be beneficial for CSME, however, risks of this
procedure include endophthalmitis and increased risk of steroid-induced intraocular pressure
(IOP) elevation. Posterior sub-Tenon injection (PST) of triamcinolone acetonide is commonly
used for inflammatory conditions of the eye and recently, has been increasingly used for
diabetic macular edema. The objective of this study is to determine whether combined
treatment with PST triamcinolone acetonide and laser photocoagulation for CSME has decreased
rates of moderate vision loss, increased visual gain, and decrease in central macular
thickness compared to laser photocoagulation alone. Both primary (no previous history of
focal/grid laser) and refractory (previous history of focal/grid laser) CMSE will be
studied. Thirty (30) eyes with primary CSME and thirty (30) eyes with refractory CSME will
be randomized into one of two groups: 1) PST/Laser group and 2) Laser alone group. All
patients will have an Optical Coherence Tomography (OCT) at the initial and final visits.
Patients assigned to PST/Laser group will use topical steroid (1% prednisolone acetate) four
times a day for two weeks. Patients who have elevated IOP with topical steroids will not
receive PST steroid injection. Following treatments, patients will be evaluated at 1 and 2
months for a dilated eye exam, visual acuity, and assessment of IOP. Moderate vision loss
(loss of 15 ETDRS letters), vision gain (in ETDRS letters), and central macular thickness
(measured by OCT) will be compared between groups. Multivariate analysis will also be used
to compare outcomes from the two arms of the study.

Inclusion Criteria:

The criteria listed below must be satisfied in order for the patient to be eligible for
the study.

- Age 25 to 80, inclusive.

- Primary CSME: CSME secondary to diabetic retinopathy as defined by the ETDRS in one
or both eyes with no previous history of focal/grid laser photocoagulation.

- Refractory CSME: CSME secondary to diabetic retinopathy as defined by the ETDRS in
one or both eyes with at least one session of focal/grid laser photocoagulation.
Additionally, the eye must have a central macular thickness of at least 300 μM
(normal, 200 μM) as measured by OCT and vision loss from baseline.

- All patients in the Hines VA Eye Clinic with suspicion of CSME will be referred
to the Hines VA Retina Clinic where they will be evaluated by a Retina
specialist (Dr. De Alba) and where the diagnosis of CSME will be confirmed by
clinical examination and fluorescein angiography.

Exclusion Criteria:

If any of the exclusion criteria listed below is/are present, the patient will not be
eligible for the study.

- Unwilling or unable to give consent.

- Unable to return for scheduled follow-up visits.

- No light perception, light perception, count fingers, or hand motion vision.

- History of glaucoma (any form).

- History of ocular hypertension.

- History of IOP elevation with ocular and/or systemic steroid treatment.

- Baseline IOP greater than 22 mmHg.

- All patients with IOP elevation greater than 22 mmHg following treatment with topical
prednisolone acetate.

- All patients with IOP elevation greater than 5 mmHg from baseline measurement
following treatment with topical Prednisolone acetate.

- Advanced proliferative diabetic retinopathy.

- History of retinal detachment in either eye.

- Any ocular disease (anterior or posterior segment) obstructing the view of the fundus
(i.e., dense cataract, vitreous hemorrhage).

- History of PST or intravitreal triamcinolone acetonide injection in either eye six
months prior to the study.

- History of 20/200 vision or worse from any cause in the fellow eye.

- Active inflammatory, infectious, or idiopathic keratitis.