Case ReportA microbubble of gas as an early indication of macular hole formationafter vitrectomy surgery for retinal detachment repairAlexander Melamud, MD,

a Dionysios Koroulakis, BS,

b and Ferdinand Rodriguez-Agramonte, MDc

Author affiliations: aThe Retina Group of Washington, Fairfax, Virginia;bGeorgetown University School of Medicine, Washington, DC;cMedstar Washington Hospital Center / Georgetown University Hospital, Washington, DC

SummaryWe present a novel case of a 67-year-old man who developed a full-thickness macular hole in the presenceof a microbubble after repair of rhegmatogenous retinal detachment.

IntroductionA microbubble of gas discovered trapped in a macularhole during postoperative recovery is an unusual clinicalpresentation described in three previous cases associatedwith macular hole repair surgery.1–3 In these previouscases, it was hypothesized that the presence of themicrobubble may have prevented successful macularhole closure after the first attempted surgical repair.1–3

Often, failed initial closure may be attributed to residualtraction because of the incomplete removal of epiretinalmembranes or the internal limiting membrane.4

We present the first case of a microbubble of gas in themacula after rhegmatogenous retinal detachment repairassociated with the de novo formation of a macular hole.We also offer a quantitative hypothesis to explain thefactors that could possibly lead to the formation of thismicrobubble.

Case ReportA 67-year-old pseudophakic man presented to the RetinaGroup of Washington clinic with a complaint of ashadow in the peripheral vision of the left eye. Thepatient’s past ocular history was notable for macula-involving rhegmatogenous retinal detachment followingpars plana vitrectomy (PPV) several years prior to pre-sentation. On examination, visual acuity was 20/60 inthe left eye. Dilated fundus examination revealed a

nasal, macula-sparing, rhegmatogenous retinal detach-ment (RRD), macular pucker, and a pseudohole. Opticalcoherence tomography (OCT) performed prior to therepair of this newly found retinal detachment showedevidence of a pseudohole (Figure 1). Surgery was per-formed with PPV, retinotomy, endodrainage, air fluidexchange, and 14% perfluoropropane (C3F8) gas infu-sion. The patient was instructed to maintain 3 days ofpostoperative positioning, alternating between lying facedown and on the left side. At the 1-month postoperative

Figure 1. Optical coherence tomographic (OCT) image prior torepair of nasal retinal detachment showing a macular pseudoholeprior to vitrectomy but absence of a full-thickness macular hole.

Published September 3, 2017.Copyright ©2017. All rights reserved. Reproduction in whole or in part in any form or medium without expressed written permission of theDigital Journal of Ophthalmology is prohibited.doi:10.5693/djo.02.2017.04.002Correspondence: Alexander Melamud, MD, MA. The Retina Group of Washington, 8505 Arlington Blvd #300, Fairfax, VA 22031-4621 (email:melamudalex@gmail.com).

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visit, ophthalmoscopy revealed a microbubble in themacula of the left eye (Figure 2). OCT 2 months aftersurgery revealed a gas microbubble causing a shadowingeffect in the fovea (Figure 3). At 10 weeks postopera-tively, OCT showed a full-thickness macular hole (Fig-ure 4). Visual acuity was 20/200 in the left eye.

Two and a half months after the nasal retinal detachmentrepair the patient underwent repeat PPV with membranepeeling and intraocular gas (15% C3F8) to repair themacular hole. Surgical repair was successful, as evi-denced by OCT (Figure 5) at 1 year after retinal detach-ment repair. The patient’s visual acuity in the left eyestabilized at 20/30.

DiscussionThe sequestration of a microbubble of gas within a reti-nal cavity after PPV is very rare.1,2 To speculate on thecause(s), it is useful to review the physics of a two-phasesystem, such as the vitreous cavity with gas and liquidphases. During the demixing of two-phase emulsion, asystem will undergo flocculation (bunching of bubbles),followed by coalescence (merging of bubbles) untilcomplete phase separation is achieved.5 In cases where amicrobubble persists, we postulate that the energeticallyfavored decrease in free energy leading to coalescence isprohibited by geometric restrictions of the particular sys-tem, which stabilize the two-bubble system. For a sys-tem of two bubbles separated by a thin film, the decreasein free energy of the formation of the semiequilibriuminterdroplet film is given by the equation

Figure 2. Fundus photograph 1 month after surgery showing amicrobubble in the fovea. The C3F8 and aqueous interface isreflecting the optic nerve and macula in the upper part of theimage.

−Δ� = 2��/� 1− �� � ,where γo/w is the interfacial tension between the continu-ous phase of the film and the droplets, and θ denotes thecontact angle between the bubbles.5 Decreased freeenergy causes a thinning of the interdroplet film, whichbecomes destabilized, or coalesces, once a critical thin-ness is breached.5 Thus, the two variables that contributeto thin film stability are interfacial (surface) tension andthe contact angle. It is known that the surface tension ofthe perfluoropropane and aqueous fluid interface is sub-stantial and favors the usual coalescence of gas bub-bles.6,7 Therefore, the only other variable that canaccount for the stabilization of the thin film is a fixedcontact angle between the two bubbles, preventing thethinning and destabilization of the film.5 The geometricboundaries facilitating such a setup with a fixed contactangle could be a particular macular hole diameter, depth,or diameter:depth ratio. Therefore, if a macular hole(full thickness, lamellar, or pseudohole) were present,this would help maintain a fixed contact angle, which inturn would stabilize the thin film and prevent the micro-bubble from coalescing with the primary gas bubble.

Whereas in previously reported cases it has beenhypothesized that the microbubble may have supportedthe persistence of the macular hole after attemptedrepair, in our case the relationship is more likely theopposite.1–3 Given the fragility of the film barrier thatseparates a microbubble from the large gas bubble in theeye, it is very unlikely that the small bubble exertedenough mechanical force against the adjacent retinal tis-sue to cause macular hole formation. If this much forcewas possible, it is more likely that the microbubblewould have coalesced with the larger bubble. We believethat it is more plausible that the formation of the macu-lar hole in this case was related to traction exerted by theepiretinal membrane and further aided by the presenceof the preexisting pseudohole. The geometry of theformed macular hole then facilitated the existence of themicrobubble.

To our knowledge, this is the first reported case of amicrobubble as an early sign of macular hole formationafter nonmacular hole repair vitrectomy surgery. Thevisualization of a microbubble in the macula of a patientrecovering from vitrectomy surgery suggests that anunderlying macular hole is present. Early surgical inter-vention may be considered in such cases to facilitate clo-sure of the macular hole and speed visual recovery. Ofnote, in the three previously reported cases of microbub-ble as well as in our case 12%–16% perfluoropropanewas used for the repair. Further understanding of the

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Figure 4. OCT image of the macula 10 weeks after surgery show-ing a full-thickness macular hole. Nasal hyperreflectivity is notedin the inner retinal layers in the presence of an epiretinal mem-brane.

Figure 5. OCT 9.5 months after retinal detachment repair showingevidence of successful surgical outcome. Patient’s vision at thistime was 20/30.

Figure 3. High-definition OCT image of the macula 2 months after surgery focusing on the gas microbubble in the fovea.

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physics in a two-phase system and its applications in ret-inal surgery will help to elucidate whether more factorsplay a role in the microbubble formation in these caseswhere perfluoropropane was used.

Literature SearchPubMed (1970-present) was searched for English-lan-guage results on January 15, 2017, using the terms gasmicrobubble and retinal microbubble. No publicationswere found with cases of de novo macular hole forma-tion with microbubble after pars plana vitrectomy forrhegmatogenous retinal detachment repair.

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2. Chow DR, Hassan T. Microbubble retention and failed macular holesurgery. Ophthalmic Surg Lasers 2001;32:243-4.

3. Kim J, Lee GH, Lee SW. A case of failed macular hole closure asso-ciated with an entrapped microbubble in the hole. J Korean Ophthal-mol Soc 2016;57:853-6.

4. Welch M, De Souza SA. Silicone oil microbubble found in failedfull-thickness macular hole closure. Retin Cases Brief Rep2014;8:132-4.

5. Friberg, S.; Yang, J. Emulsion stability. In: Sjoblom, J., editor.Emulsions and Emulsion Stability. Surfactant Science Series V. 61New York, NY: Marcel Dekker; 1996. p. 1-8.

6. de Juan E, McCuen B, Tiedeman J. Intraocular tamponade and sur-face tension. Surv Ophthalmol 1085;30:47-51.

7. Shaheeda M, Lai TY. Intraocular gas in vitreoretinal surgery. HongKong J Ophthalmol 2010;14:8-13.

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