NG:YAG LASER HYALOIDOTOMY FOR PREMACULAR HEMORRHAGE IN BOTH EYES IN A PATIENT WITH ACUTE MYELOBLASTIC LEUKEMIA

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Premacular hemorrhages (PMHs) lead to sudden and profound vision loss.They are caused by retinal vascular disorders (diabetic retinopathy or vein occlusion), age-related macular degeneration, Valsalva retinopathy, macroaneurysms, etc. [1][2][3][4][5][6].Up to 49 % of patients with leukemia suffer from hemorrhages in the ocular fundus, of them 6 % have PMHs [7].In most cases these lesions resolve spontaneously within a few weeks or months, depending on the size.But for socially active patients or those with hemorrhages in both eyes or in their only healthy eye recovery should be expedited.Besides, vision restoration has a positive psychological impact on patients with severe comorbidities.Of all known treatment approaches, including pneumatic displacement therapy with tissue plasminogen activator [8,9], vitrectomy [10], and Ng:YAG laser hyaloidotomy [11][12][13][14], the latter is the safest and the most accessible.
Below we describe a case of a 23-year old patient with acute myeloblastic leukemia with PMHs in both eyes resulting in profound visual impairment.Ng:YAG laser posterior hyaloidotomy was performed on both eyes of the patient, with a few minute break between the procedures.This case presents a particular interest, because due to the location of the hemorrhage inferior margin in the fovea of the patient's left eye, it was decided to make the opening above the fovea to avoid retinal damage.For the right eye the puncture site was conventionally chosen at the inferior margin of the lesion.Post-treatment follow-up revealed that hemorrhages resorbed differently in the right and left eyes.

Case description
A 23-year old patient with acute myeloblastic leukemia undergoing polychemotherapy presented with profound vision loss following premacular hemorrhages in both eyes six weeks earlier.Upon admission best corrected visual acuity (Vis) was 0.1 for the right eye (OD) and 0.05 for the left eye (OS); intraocular pressure (IOP) was as follows: IOP OD = 20 mmHg, IOP OS = 20 mmHg.In both eyes preretinal hemorrhages were observed in the posterior pole of the ocular fundus, extending to the fovea.The size of the lesion area in the macula was about 5 diameters of the optic disc in the right eye and 3 diameters of the disc in the left eye.We performed Ng:YAG КЛИНИЧЕСКИЙ СЛУЧАЙ ОФТАЛЬМОЛОГИЯ laser posterior hyaloidotomy above the lesion area in both eyes using the VISULAS YAG III platform (Carl Zeiss Meditec AG, Germany) with a wavelength of 1064 nm and spot diameter of 10 µm in two single bursts at Е = 2 mJ in each eye with a few minute break between the procedures.The central fovea lies 500 µm below the horizontal line bisecting the optic disc [15].In our experience, the opening in the hyaloid membrane should be made no closer than 1000 µm to the central fovea to avoid damage to the latter.Therefore, it was decided to perform hyaloidotomy of the right eye at the inferior margin of the lesion, 2500 µm below the horizontal line (Fig. 1, А).But as the inferior margin of the hemorrhage in the left eye was in the foveal area, we decided to make an opening 1000 µm above the fovea, or 500 µm above the horizontal line (Fig. 1, B).
A week after hyaloidotomy best corrected Vis OD was 0.7, best corrected Vis OS was 0.08, IOP OD was 19 mmHg, IOP OS was 19 mmHg.Areas of residual hemorrhage were observed in the macula of both eyes (Fig. 2, А).Optical coherence tomography (OCT) performed with the Avanti RTVue 100 scanner (Optovue, USA) revealed highly reflective opacities in the vitreous and an opening in the partially detached posterior hyaloid membrane in the right eye AND highly reflective opacities above the fovea (areas of residual hemorrhage) and an opening in the partially detached posterior hyaloid membrane in the left eye (Fig. 3, А).Results 5 weeks after hyaloidotomy: best corrected Vis OD = 0.7, best corrected Vis OS = 0.1, IOP OD = 18 mmHg, IOP OS = 16 mmHg; complete hemorrhage diffusion in the right eye's macula, small areas of residual hemorrhage in the left eye's fovea (Fig. 2, B).Results 14 weeks after hyaloidotomy: corrected Vis OD = 1.0, corrected Vis OS = 0.6, IOP OD = 18 mmHg, IOP OS = 16 mmHg, complete resorption of the hemorrhage in the right eye's macula, small areas of residual hemorrhage in the left eye's macula (Fig. 2, C).OCT revealed almost complete resorption of highly reflective opacities above the fovea in both eyes (Fig. 3, B).No changes in visual acuity were seen in further follow-up examinations.

Case discussion
Ng:YAG laser posterior hyaloidotomy is an effective and safe technique for treating premacular hemorrhages.Traditionally, it is performed at the inferior margin of the lesion for rapid blood drainage, which is assisted by gravity and oscillations of the detached posterior hyaloid membrane above the lesion that are in turn triggered by the oscillations of the vitreous accompanying normal eye movements.The opening must be far enough from the fovea to avoid damage to the latter.In the described clinical case indications for hyaloidotomy of the right eye were unquestionable.It was risky, however, to perform the procedure at the inferior margin of the lesion in the left eye.A decision was made to make an opening above the fovea.Obviously, considering such location of the opening, gravity will not facilitate blood drainage from the lesion area below the puncture site.But we assumed that blood drainage could be assisted by small oscillations of the detached posterior hyaloid membrane above the lesion that are a result of oscillations of the vitreous that accompany eye movements.The followup examinations confirmed our assumptions.But as we had expected, resorption of the hemorrhage in the left eye took longer (1 month longer) than in the right eye, in spite of a smaller lesion size.

CONCLUSIONS
Ng:YAG laser posterior hyaloidotomy performed above the lesion area is an effective and safe technique for treating premacular hemorrhages in patients with acute myeloblastic leukemia undergoing chemotherapy.
The case presented above demonstrates the possibility of treating premacular hemorrhages extending to the fovea with Ng:YAG laser puncture.The opening should be made above the fovea, unlike standard openings usually made at the inferior margin of the lesion.However, such location of the puncture site will result in slower hemorrhage resorption.

Fig. 1 .Fig. 2 .
Fig. 1.Fundus photos of the right (А) and left (B) eyes of the patient upon admission to the clinicFig.2. Fundus photos of the right (OD) and left (OS) eyes of the patient (А) 1 week, (B) 5 weeks and (C) 14 weeks after Ng:YAG laser posterior hyaloidotomy OD

Fig. 3 .
Fig. 3. Optical coherence tomography of the macula of the right (OD) and left (OS) eyes of the patient (А) 1 week and (B) 14 weeks after Ng:YAG laser hyaloidotomy