effects of triamcinolone acetonide make it an interesting potential therapeutic agent in an attempt to prevent retinal pigment epithelial metaplasia in eyes threatened with foveal exudates.102

CASE 3: In the case of extreme macular thickening (OCT central subfield thickness = 992 mm) and 20/ 160 visual acuity, the management recommendations of most of the doctors mirrored their responses to case 2. However, doctor A diverged from the use of laser in this severe case of DME, preferring the use of IVB/ IVT. The literature supports the notion that poor visual acuity from DME is prognostic of poor visual outcome despite intervention with laser.103 Thus, it is not surprising that a more aggressive therapeutic stance may be taken in such cases. In the short term, IVB/IVT does appear to have a more rapid onset of effect compared with macular laser.96,48 However, the long-term effect of persistent focal/grid macular laser was shown to be superior to IVT by the DRCR.net.48 Randomized controlled trials are needed to better define the role of adjunctive use of IVB and IVT.l

16.13Case 13: Management Options for a Complicated Case of Proliferative Diabetic Retinopathy with Severe Fibrovascular Proliferation, Sub-clinical Macular Edema, and Recent Vitreous Hemorrhage

16.13.1 Definition of the Problem

Fig. 16.50 Red-free photograph of the left eye of case 13. Disk neovascularization, vitreous hemorrhage, a macular epiretinal membrane, and traction by a membrane on the nasal disk margin are seen

A 48-year-old female with type 1 diabetes mellitus of 30 years duration has previously undergone panretinal photocoagulation (PRP) with a total of 1,241 spots for proliferative diabetic retinopathy (PDR) and vitreous hemorrhage involving the left eye 6 weeks ago. Presently, she is phakic and her visual acuity is 20/20 OD and 20/30 OS. Her vitreous hemorrhage has cleared somewhat and her fundus photograph (Fig. 16.50), fluorescein angiogram (Fig. 16.51), and optical coherence tomogram (Fig. 16.52) are shown. What management recommendations would you have for this eye?

l Discussed by Scott E. Pautler, M.D.

Fig. 16.51 Mid-phase frame from the fluorescein angiogram of the left eye of case 13. Hyperfluorescent leakage from the disk neovascularization, parafoveal intraretinal hyperfluorescence, and temporal midperipheral capillary nonperfusion are seen

16.13.2 Discussion

This patient has severe fibrovascular proliferation with vitreous hemorrhage from PDR accompanied by diabetic macular edema (DME). All of the chapter authors who reviewed this case recommended additional PRP. Although this patient has already received a PRP laser of 1,241 spots,

the details of the laser procedure were not given. If a wide-angle contact lens was used with a laser setting of 200 mm, this laser treatment does not equate to Early Treatment Diabetic Retinopathy Study (ETDRS) PRP. In the ETDRS, 1,200–1,600 laser burns were usually applied using a 500 mm laser setting with a Goldmann 3-mirror lens.104 An equivalent PRP treatment using a 200 mm laser setting with a wide-angle lens (e.g., Volk H-R Wide Field, Volk SuperQuad 160, or Ocular Instruments Mainster PRP 165) would require approximately 3,000 laser spots (see Table 9.6). Moreover, there are proponents for the applica-

tion of PRP exceeding ETDRS guidelines in cases of severe PDR.105,106 As this case possesses high-

risk features for visual loss in PDR, such as severe fibrovascular proliferation with vitreous hemorrhage and DME in a patient with type 1 diabetes,

a complete 360 degree PRP extending anterior to the equator may be in order.107–110 Finally, the

literature supports the prompt completion of PRP in this case given the presence of high-risk features.104

This case is complicated by the presence of diabetic macular edema and preretinal membrane formation with central subfield macular thickness (CSMT) of 281 mm. The chapter authors who reviewed this case expressed concern about the potential for

exacerbation of DME by additional laser and were

generally inclined to offer adjunctive intravitreal pharmacotherapy.111,102 There was divided opinion

on the use of IVT vs. IVB. One group preferred IVB to avoid the risk of steroid-induced cataract and glaucoma.102 Those who preferred IVT wished to avoid IVB-induced vitreoretinal traction retinal detachment.112 Although there are no evidence-based guidelines at this time, there is support in the literature for

the efficacy of both IVB and IVT in reducing DME in the short term.102,112 Macular laser should be considered for long-term control of DME.29,48

The presence of severe fibrovascular proliferation (FVP) and preretinal membrane formation in this case places the retina at risk for traction retinal detachment. The fundus photograph (Fig. 16.51) shows early evidence of preretinal traction in the way of mild macular heterotopia with inferior macular dragging, though no history of metamorphopsia or diplopia was given. The presence of severe FVP prompted one group of doctors to avoid the use of IVB for DME. However, it appears that progressive traction retinal detachment may

occur in PDR following IVB, PRP, or in the natural history of PDR.113,114,112,110 Although there is rea-

son to believe that the anti-fibrotic effects of triamcinolone acetonide may mitigate this risk, there is no definitive evidence to date.102