Purpose: To evaluate the effectiveness of focal laser for the treatment of diabetic macular edema (DME) performed by ophthalmology residents.
Methods: This retrospective chart review studies DME patients treated in a resident clinic with focal laser. Visual acuity (VA), OCT central subfield thickness (CST), and maximum subfield thickness (MST) at initial, 1-month, and 6-month visits were recorded.
Results: For 32 reviewed patients, the average VA was 20/58 initially and 20/39 at 6 months (p=0.18). Mean CST was 311 µm initially and 305 µm at 6 months (p=0.09). Mean MST was 413 µm initially and 382 µm at 6 months (p=0.007). Factors favoring success are initial CST \u3c400 µm, treatment of localized microaneurysms, and prior focal laser treatments.
Conclusion: Focal laser performed by residents was effective in decreasing MST and maintained visual acuity.  Initial CST, localized microaneurysms, and repeat focal treatment predicted improved outcomes

Albert, Desiree, MD

Lin, Xihui, MD

Syeda, Sarah, MD

Tukel, Matthew

Vaishampayan, Anita

English

Digital Commons@Wayne State University

Wayne State University Medical Student Research Symposium School of Medicine March 2020 Focal Laser Photocoagulation for Diabetic Macular Edema Done by Resident Physicians: Predictors of Effective Treatment Matthew Tukel fh1837@wayne.edu Desiree Albert MD Henry Ford Health System Sarah Syeda MD Kresge Eye Institute Anita Vaishampayan Wayne State University Xihui Lin MD Kresge Eye Institute Follow this and additional works at: https://digitalcommons.wayne.edu/som_srs  Part of the Medicine and Health Sciences Commons Recommended Citation Tukel, Matthew; Albert, Desiree MD; Syeda, Sarah MD; Vaishampayan, Anita; and Lin, Xihui MD, "Focal Laser Photocoagulation for Diabetic Macular Edema Done by Resident Physicians: Predictors of Effective Treatment" (2020). Medical Student Research Symposium. 3. https://digitalcommons.wayne.edu/som_srs/3 This Research Abstract is brought to you for free and open access by the School of Medicine at DigitalCommons@WayneState. It has been accepted for inclusion in Medical Student Research Symposium by an authorized administrator of DigitalCommons@WayneState.  1 Focal Laser Photocoagulation for Diabetic Macular Edema Done by Resident Physicians: Predictors of Effective Treatment  Desiree Albert MD1, Kevin Bubel MD2, Sarah Syeda, MD 3, Matthew R. Tukel BS 3, Anita Vaishampayan, Kim Le MD 1,2, Xihui Lin MD 2,3  1Henry Ford Health System; Detroit, MI, USA 2University of Texas Southwestern Medical Center, Dallas, TX, USA 3Kresge Eye Institute; Detroit, MI, USA                  Corresponding Author: Matthew R. Tukel 3150 Woodward Ave. 521 Detroit Mi, 48201 (248) 766-1619 Mtukel@med.wayne.edu      2 Abstract:  1 Purpose: To evaluate the effectiveness of focal laser for treatment of diabetic macular edema (DME) 2 performed by ophthalmology residents. 3 Methods: Chart review of DME patients treated in a resident clinic with focal laser. Visual acuity (VA), 4 OCT central subfield thickness (CST), and maximum subfield thickness (MST) at initial, 1 month, and 6 5 month visits were recorded. 6 Results: For 32 reviewed patients, average VA was 20/58 initially and 20/39 at 6 months (p=0.18). Mean 7 CST was 311 µm initially and 305 µm at 6 months (p=0.09). Mean MST was 413 µm initially and 382 8 µm at 6 months (p=0.007). Factors favoring success are: initial CST <400 µm, treatment of localized 9 microaneurysms, and prior focal laser treatments.   10 Conclusion: Focal laser performed by residents was effective in decreasing MST and maintained visual 11 acuity.  Initial CST, localized microaneurysms and repeat focal treatment predicted improved outcomes. 12  13  14  15  16  17  18  19  20  21  22  23  24  25  3 Introduction 26   Diabetic macular edema (DME) is the most common cause of vision loss in diabetic retinopathy.1 27 It is a prevalent disease, affecting 7% of people with diabetes.2 The mechanism for edema in diabetic 28 retinopathy is due to abnormal vascular permeability.3 As in diabetic retinopathy, the greatest modifiable 29 risk factor for the development of DME is hyperglycemia.4 DME is diagnosed by the presence of macular 30 thickening observed via slit lamp biomicroscopy, stereoscopic fundus photos, or on optical coherence 31 tomography (OCT) (figure 1). Other exam findings such as hard exudates in the presence of 32 microaneurysms and blot hemorrhages within one disc diameter of the fovea have been utilized for 33 diagnosis as well.4 Fluorescein angiography (FA) can also aid in diagnosis. It will show vascular leakage 34 in the setting of edema, which frequently correlates well with OCT findings.5  35   Treatment of DME, with goals of immediate and sustained visual improvement and prevention of 36 vision loss, has evolved through the years. The first available treatment option began in 1985 when the 37 Early Treatment Diabetic Retinopathy Study established the effectiveness of laser photocoagulation for 38 DME.6 Laser can be performed in focal pattern, targeting specific leaking microaneurysms, or in a grid 39 pattern to target areas of more diffuse leakage.6 Our study concentrates on focal laser photocoagulation. 40   While laser was the only treatment option available for 20 years, there are now several other 41 modalities available. The advent of intravitreal anti-vascular endothelial growth factor (VEGF) 42 medications, beginning with pegaptanib in 2005 introduced a second treatment option, particularly useful 43 for center-involving DME that is not amenable to laser treatment.7 Currently, ranibizumab, aflibercept, 44 and the off-label use of bevacizumab, are available anti-VEGF agents, and these agents have dramatically 45 changed the treatment of DME. The release of the Diabetic Retinopathy Clinical Research Network 46 (DRCR.net) Protocol I data, demonstrated the role of intravitreal anti-VEGF agents in combination with 47 focal/grid laser treatment.8    48   There are additional treatment options that may be utilized, particularly in refractory cases.  This 49 includes intravitreal triamcinolone, which was superior to laser alone in pseudophakic eyes when studied 50 in DRCR.net protocol I, as well as various other ocular steroid formulations.9 Lastly, DME that is 51  4 associated with posterior hyaloid traction and/or epiretinal membrane may be amenable to improvement 52 with pars plana vitrectomy.10  53   Given the multitude of treatment options and various treatment algorithms that have been studied, 54 the decision for when focal laser is indicated is very practitioner-dependent and frequently based on 55 personal experience. Our study analyzes focal laser treatments performed by multiple physicians in an 56 inner-city population to identify patient selection factors and treatment parameters that correlated with 57 successful outcomes. 58   59 Methods 60   Patients with DME were selected from outpatient visits with multiple physicians at Parkland 61 Memorial Hospital (Dallas, TX). The study was conducted in accordance with the World Medical 62 Association Declaration of Helsinki. 63   The study consisted of 32 patients, 24 (75%) of which were male. The population was 64 predominantly Hispanic (59.4%), and the average age was 65 years old. Average hemoglobin A1c was 65 8.3%. See table 1 for additional demographic characteristics. 66   Patient selection for receiving focal laser treatment was physician dependent, and these selection 67 factors were analyzed in the study. Exclusion criteria included macula edema not secondary to diabetic 68 retinopathy (e.g. retinal vein occlusion, Irvine-Gass Syndrome, uveitic macular edema), lack of return for 69 the 1 month follow-up appointment, or if pre-treatment or post-treatment OCT’s (Heidelberg Spectralis) 70 were not available. 71   For each selected patient, laser treatment was performed with an Iridex 532 nm green laser 72 through a slit-lamp delivery system in single spots without pattern scanning. The lens used for all 73 treatments was a Volk Area Centralis contact lens. Treatment parameters including laser power and 74 duration settings, spot size, number of shots, and pattern of treatment were analyzed. 75   Patients returned for 1-month follow-up, with the primary outcomes examined at that visit 76 including visual acuity change, OCT central subfield thickness (CST) change, and maximal subfield 77  5 thickness (MST) change as compared to pre-treatment values. MST was analyzed because the goal of 78 many focal laser treatments was to target a non-central area of leakage in order to prevent future central 79 involvement. 80  81 Results 82   Visual acuity was recorded on logMAR scale, with a pre-treatment average visual acuity of 0.42 83 (corresponding to 20/52) and 1-month post treatment average visual acuity of 0.34 (corresponding to 84 20/44). The average CST was 322.26 µm pre-treatment and 325.81 µm post-treatment, while the average 85 MST did improve marginally from 418.29 µm to 407.74 µm. Average laser parameters used were 86 96.78mW power, 0.1 second duration, 91.38 µm spot size, and shot count of 4.43. 87   When comparing patients with less than 400 µm CST (n = 57) pre-treatment to patients with 88 greater than 400 µm (n = 10), there was a statistically significant (p = 0.0001) difference in CST change 89 and MST change at 1 month, favoring those patients with thinner pre-treatment CST. This is attributable 90 to the fact that in eyes with CST greater than 400 µm, significant amount of the leakage was centrally 91 located and was not amenable to focal laser. This OCT improvement did not, however, correlate with 92 statistically significant visual acuity improvement advantage for those with less than 400 µm pre-93 treatment.  See Table 2 for detailed study results. 94  Conclusions 95 For patients who had less than 5 microaneurysms targeted with laser treatment, there was a 96 statistically significant difference in visual acuity, CST, and MST outcomes at 1 month as compared to 97 other targets of treatment. In those patients with fewer microaneurysms targeted, the source of leakage 98 was more focal and therefore responded better to laser treatment. 99   Due to limited resources at our county hospital, FA was only able to be obtained prior to laser 100 treatment in 1/3 of the cases where the source of leakage was uncertain (i.e. many candidate 101 microaneurysms), but there was no significant relationship found between visual acuity or OCT outcomes 102 at 1 month whether the patient had an FA conducted prior to treatment or not. 103  6   Laser parameters were evaluated, and patients were found to have worse outcomes when power 104 settings outside the range of 80-100 mW were utilized, with worse visual acuity, CST, and MST 105 outcomes at 1 month (p = 0.039, 0.022, and 0.014, respectively), as compared to those treatments 106 conducted within the 80-100 mW range. This is likely due to laser power of less than 80 mW being 107 inadequate to sufficiently coagulate microaneurysms or induce significant local photo-chemical changes, 108 and power greater than 100 mW likely inducing more local inflammatory changes which temporarily 109 worsened the swelling at 1 month.   110   Visual acuity outcomes at 1 month were worse for patients who had previous focal or grid laser 111 treatment prior to this study as compared to those who had no prior laser (p = 0.07). 112   There was no significant correlation found between hemoglobin A1c level and visual acuity, 113 CST, or MST outcomes at 1 month follow up. There was also no correlation found between number of 114 intravitreal bevacizumab (Avastin) injections received in the previous 6 months and post-laser 115 outcomes.     116   Overall, focal laser photocoagulation for DME in an inner-city county hospital population 117 improved visual acuity and stabilized macular swelling at 1 month post-treatment. Predictive factors for 118 favorable focal laser outcomes included pre-treatment CST of less than 400 µm, treatment targeting fewer 119 than 5 microaneurysms in a focal area of swelling, and using laser parameters of power between 80 mW 120 and 100 mW. Prior fluorescein angiography, prior macular laser treatments, and hemoglobin A1c 121 percentage did not correlate with improvement at 1 month. 122  123 Conflict of interest/Funding Statement: The authors declare that there is no conflict of interest. The 124 authors received no financial support for the research, authorship, and/or publication of this article. 125  126  127  128  129  7 References 130 1. Patz A, Schatz H, Berkow JW, Gittelsohn AM, Ticho U. Macular edema--an overlooked complication of diabetic 131 retinopathy. Trans Am Acad Ophthalmol Otolaryngol 1973;77:OP34-42. 132 2. Yau JW, Rogers SL, Kawasaki R, et al. Global prevalence and major risk factors of diabetic retinopathy. Diabetes 133 Care 2012;35:556-64. 134 3. Bresnick GH. Diabetic maculopathy. A critical review highlighting diffuse macular edema. Ophthalmology 135 1983;90:1301-17. 136 4. Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related 137 vision loss. Eye Vis (Lond) 2015;2:17. 138 5. Kang SW, Park CY, Ham DI. The correlation between fluorescein angiographic and optical coherence tomographic 139 features in clinically significant diabetic macular edema. Am J Ophthalmol 2004;137:313-22. 140 6. Photocoagulation for diabetic macular edema. Early Treatment Diabetic Retinopathy Study report number 1. Early 141 Treatment Diabetic Retinopathy Study research group. Arch Ophthalmol 1985;103:1796-806. 142 7. Cunningham ET, Jr., Adamis AP, Altaweel M, et al. A phase II randomized double-masked trial of pegaptanib, an 143 anti-vascular endothelial growth factor aptamer, for diabetic macular edema. Ophthalmology 2005;112:1747-144 57. 145 8. Elman MJ, Ayala A, Bressler NM, et al. Intravitreal Ranibizumab for diabetic macular edema with prompt versus 146 deferred laser treatment: 5-year randomized trial results. Ophthalmology 2015;122:375-81. 147 9. Diabetic Retinopathy Clinical Research N, Elman MJ, Aiello LP, et al. Randomized trial evaluating ranibizumab 148 plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema. Ophthalmology 149 2010;117:1064-77 e35. 150 10. Diabetic Retinopathy Clinical Research Network Writing C, Haller JA, Qin H, et al. Vitrectomy outcomes 151 in eyes with diabetic macular edema and vitreomacular traction. Ophthalmology 2010;117:1087-93 152 e3. 153  154  155  8 Figure legends 156 Figure 1 - OCT images from a patient who received focal grid laser treatment.  1A - pre-treatment image 157 with temporal macular edema.  1B - 1 month post-treatment image with improved temporal macular 158 edema.  159  160 

Focal Laser Photocoagulation for Diabetic Macular Edema Done by Resident Physicians: Predictors of Effective Treatment

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Focal Laser Photocoagulation for Diabetic Macular Edema Done by Resident Physicians: Predictors of Effective Treatment

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