Six-month postoperative outcomes of intraoperative OCT-guided surgical cystotomy for refractory cystoid macular edema in diabetic eyes

Clinicopathological findings in refractory diabetic macular edema: A case report

The present study describes the case of a patient with refractory diabetic cystoid macular edema who underwent vitrectomy with en bloc removal of the cystoid lesion component. The current study also performed histopathological and immunohistochemical analyses of the cystoid lesion component to assess fibrin/fibrinogen and advanced glycation end-products (AGEs) immunoreactivity. A 69-year-old Japanese man presented with visual loss in the left eye due to residual cystoid macular edema (CME) refractory to anti-vascular endothelial growth factor therapy. Best-corrected visual acuity was 1.2 in the right eye (OD) and 0.5 in the left eye (OS). Fundus examination showed dot hemorrhages and hard exudates in the peri-macular region with pan-retinal photocoagulation scars in both eye. Swept-source optical coherence tomography revealed CME with slight hyperreflectivity in the cyst OS. A total of 3 months after the initial visit, pars plana vitrectomy was performed, and the translucent solidified component within the cystoid lesion was isolated. Histopathologically, the excised component was elliptical in shape, measuring 0.7x0.4 mm and exhibited homogeneous eosinophilic material without cellular components. No membranous structure was observed surrounding the component. Immunohistochemistry demonstrated that the tissue was positive for fibrin/fibrinogen and weakly positive for AGEs, but was negative for glial fibrillary acidic protein, type 1 collagen and receptor for AGEs. To the best of our knowledge, the present case report is the first to histopathologically examine the contents of refractory CME, and to immunohistochemically demonstrate that fibrin in diabetic CME may be post-translationally modified by AGEs. These results suggested that fibrin in CME may escape degradation by plasmin due to post-translational modifications.

Current Treatments for Diabetic Macular Edema

Diabetic retinopathy is a major retinal disorder and a leading cause of blindness. Diabetic macular edema (DME) is an ocular complication in patients with diabetes, and it can impair vision significantly. DME is a disorder of the neurovascular system, and it causes obstructions of the retinal capillaries, damage of the blood vessels, and hyperpermeability due to the expression and action of vascular endothelial growth factor (VEGF). These changes result in hemorrhages and leakages of the serous components of blood that result in failures of the neurovascular units (NVUs). Persistent edema of the retina around the macula causes damage to the neural cells that constitute the NVUs resulting in diabetic neuropathy of the retina and a reduction in vision quality. The macular edema and NVU disorders can be monitored by optical coherence tomography (OCT). Neuronal cell death and axonal degeneration are irreversible, and their development can result in permanent visual loss. Treating the edema before these changes are detected in the OCT images is necessary for neuroprotection and maintenance of good vision. This review describes the effective treatments for the macular edema that are therefore neuroprotective.

The Correlation between the Increased Expression of Aquaporins on the Inner Limiting Membrane and the Occurrence of Diabetic Macular Edema

Purpose

Diabetic macular edema (DME) is a major cause of vision loss in patients with diabetic retinopathy; this study is aimed at comparing the expression of aquaporins (AQPs) on the inner limiting membranes (ILMs) of various vitreoretinal diseases and investigating the role of aquaporins expressed on the ILMs in mediating the occurrence of DME.

Methods

The whole-mounted ILM specimens surgically excised from patients with various vitreoretinal diseases (idiopathic macular hole, myopic traction maculopathy, and diabetic retinopathy) were analyzed by immunohistochemistry (IHC). The distribution and morphology of AQP4, AQP7, and AQP11 on the ILMs were correlated with immunohistochemical staining characteristics. Moreover, immunofluorescence of AQP4 was performed on the ILM specimens of the patient in four groups: the control group, negative control group, no DME group, and DME group. The immunofluorescence intensity value of AQP4 was measured using ImageJ. The difference between the four groups and the correction between the immunofluorescence value and central foveal thickness (CFT) were analyzed.

Results

In IHC sections, the expression of AQP4, AQP7, and AQP11 on ILMs of diabetic retinopathy (DR) with macular edema, respectively, seemed to be more abundant than in the idiopathic macular hole (iMH) and myopic traction maculopathy (MTM). Moreover, markedly higher fluorescence intensity of AQP4 of ILMs was determined in the DME group (51.05 ± 5.67) versus the other three groups (P < 0.001). A marked positive association was identified between the fluorescence intensity of AQP4 and CFT (r = 0.758; P = 0.011).

Conclusions

AQP4, AQP7, and AQP11 can be expressed on human ILM in vivo. The increased expression of AQPs on the ILMs of DR may be associated with the occurrence of DME. Moreover, the degree of DME may be positively correlated with the expression of AQP4 on the ILMs.

Clinical applications for intraoperative optical coherence tomography: a systematic review

In this systematic review, we provide an overview of the current state of intraoperative optical coherence tomography (iOCT). As iOCT technology is increasingly utilized, its current clinical applications and potential uses warrant attention. Here, we categorize the findings of various studies by their respective fields, including the use of iOCT in vitreoretinal surgery, corneal surgery, glaucoma surgery, cataract surgery, and pediatric ophthalmology. The trend observed in recent decades towards performing minimally invasive ophthalmic surgery has caused practitioners to recognize the limitations of using a conventional surgical microscope for intraoperative visualization. Thus, the superior visualization provided by iOCT can improve the safety of these surgical techniques and promote the development of new minimally invasive ophthalmic surgeries. Landmark prospective studies found that iOCT can significantly affect surgical decision making and can cause a subsequent change in surgical strategy, and the use of iOCT has potential to improve surgical outcome. Despite these advantages, however, iOCT is still a relatively new technique, and beginning users of iOCT can encounter limitations that can preclude their reaching the full potential of iOCT and in this respect several improvements are needed.

LONG-TERM EFFECT OF CYSTOTOMY WITH OR WITHOUT THE FIBRINOGEN CLOT REMOVAL FOR REFRACTORY CYSTOID MACULAR EDEMA SECONDARY TO DIABETIC RETINOPATHY

PURPOSE

To show the long-term effect of cystotomy with or without fibrinogen clot removal for refractory cystoid macular edema secondary to diabetic retinopathy.

METHODS

Retrospective analyses of the medical records of 30 eyes of 30 patients with refractory cystoid macular edema secondary to diabetic retinopathy who had followed up for 12 months after the surgery were performed.

RESULTS

There were 15 men and 15 women. The mean ± SD age was 68.4 ± 7.9 years. The best-corrected visual acuity (logarithm of the minimal angle of resolution) at 12 months after the surgery (0.33 ± 0.25, Snellen equivalent, 20/42) was statistically better than the preoperative best-corrected visual acuity (0.45 ± 0.33, Snellen equivalent, 20/56) (P < 0.01). The central sensitivity on microperimetry (dB) was not statistically changed between preoperatively (24.0 ± 4.9) and 12 months after the surgery (24.1 ± 4.0) (P = 0.75). The central retinal thickness on optical coherence tomography (μm) at 12 months after the surgery (300.3 ± 99.0) was statistically improved compared with the preoperative central retinal thickness (565.6 ± 198.7) (P < 0.01). During the follow-up period, cystoid macular edema relapsed in seven of 30 eyes. The preoperative cystoid cavity reflectivity on optical coherence tomography in patients with fibrinogen clot removal (n = 16) was significantly higher than that in patients without fibrinogen clot removal (n = 14) (P < 0.04).

CONCLUSION

The cystotomy with or without fibrinogen clot removal may be a promising treatment option for refractory cystoid macular edema secondary to diabetic retinopathy.

EFFECTIVENESS OF EN BLOC REMOVAL OF FIBRINOGEN-RICH COMPONENT OF CYSTOID LESION FOR THE TREATMENT OF CYSTOID MACULAR EDEMA

PURPOSE

To introduce the methodology and outcomes of en bloc removal of the component of cystoid lesion during pars plana vitrectomy as a novel approach for the treatment of cystoid macular edema and show evidence that the component is an aggregation of fibrinogen by mass spectrometry analysis.

METHODS

The surgical en bloc extraction of the component of cystoid lesion was performed for cystoid macular edemas secondary to diabetic retinopathy and retinal vein occlusion. Perioperative change of best-corrected decimal visual acuity, and the central retinal thickness and the continuity of subfoveal ellipsoid zone and external limiting membrane on optical coherence tomography were evaluated. Mass spectrometry was performed for the identification of protein constituting the component.

RESULTS

Six eyes from six patients were included in the study. In all cases, central retinal thickness was improved after the surgery and remained stable during the follow-up period. Best-corrected decimal visual acuity and the continuity of ellipsoid zone and external limiting membrane were kept in all cases during the follow-up period. The mass spectrometry analysis disclosed that the component was composed of fibrinogen.

CONCLUSION

The en block removal of the component of cystoid lesion combined with pars plana vitrectomy may be a promising option for treatment of cystoid macular edema. The component of cystoid lesion is presumably a fibrinogen aggregate.

What Is the Impact of Intraoperative Microscope-Integrated OCT in Ophthalmic Surgery? Relevant Applications and Outcomes. A Systematic Review

Background: Optical coherence tomography (OCT) has recently been introduced in the operating theatre. The aim of this review is to present the actual role of microscope-integrated optical coherence tomography (MI-OCT) in ophthalmology. Method: A total of 314 studies were identified, following a literature search adhering to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. After full-text evaluation, 81 studies discussing MI-OCT applications in ophthalmology were included. Results: At present, three microscope-integrated optical coherence tomography systems are commercially available. MI-OCT can help anterior and posterior segment surgeons in the decision-making process, providing direct visualization of anatomic planes before and after surgical manoeuvres, assisting in complex cases, and detecting or confirming intraoperative complications. Applications range from corneal transplant to macular surgery, including cataract surgery, glaucoma surgery, paediatric examination, proliferative diabetic retinopathy surgery, and retinal detachment surgery. Conclusion: The use of MI-OCT in ophthalmic surgery is becoming increasingly prevalent and has been applied in almost all procedures. However, there are still limitations to be overcome and the technology involved remains difficult to access and use.