Macular retinal folds are a rare yet grave complication of surgical rhegmatogenous retinal detachment (RRD) repair [1]. Macular folds were first described by Pavan in 1984 following a scleral buckling procedure combined with intravitreal gas tamponade. The literature on retinal folds associated with RRD surgery is scarce and mostly comprises clinical case reports. In 1991 Van Meurs et al. analyzed the outcomes of RRD surgery in 137 patients; of them, 4 (2.8%) patients had developed retinal folds. According to a 2011 publication by Isaico et al., 3 (1.96%) of 153 examined patients had retinal folds after surgical RRD repair. The primary risk factors for postoperative retinal folds include intraocular gas injection, acute RRD, large wide explants, bullous RRD with tears in the superior quadrants, transscleral drainage of subretinal fluid, and RRD extending into the macular zone [1–6].

Clinical symptoms vary depending on the location and severity of retinal folding. Macular retinal folds manifest as visual field defects, diplopia, metamorphopsia, and reduced visual acuity, whereas peripheral retinal folds can be asymptomatic [3, 6–10].

Until recently, retinal folds were classified in the literature by their location (posterior and macular), shape and orientation (arcuate), pathogenesis (compression folds), clinical features (dry) or were referred to simply as retinal folds [11].

Then, retinal fold morphology was elucidated by optical coherence tomography (OCT). Two types of retinal folds were distinguished: partial-thickness (involving the inner or outer retina) and full-thickness folds. The latter involve all layers of the retinal neuroepithelium and appear as a convex, deformed retina on OCT images. OCT features of the full-thickness retinal fold include contact between the basal segments of adjacent retinal layers, disorganized retinal architecture, structural changes in the external limiting membrane, the connecting cilium between the outer and inner photoreceptor segments, the outer nuclear layer, the outer plexiform layer and not uncommonly in the overlying layers, as well as formation of hyperreflective areas [11, 12]. Inner retinal folds involve the inner retinal layer and appear on OCT as a pronounced distortion of the retinal profile presenting as internal limiting membrane to internal limiting membrane apposition. Outer retinal folds appear as multiple small vertically oriented hyperreflective lesions over the retinal pigment epithelium (RPE), extending into the outer nuclear layer [11, 12].

According to the literature, there is no unified treatment strategy for retinal folds. The outcomes also vary, from complete resolution of the fold and visual function recovery to partial regression with minimal or moderate vision recovery to severe irreversible retinal damage. In most cases, macular retinal folds persist causing irreversible loss of visual acuity and metamorphopsia [3–6, 10, 13]. Besides, patients with previously stable retinal folds are reported to develop late recurrent retinal detachment resulting from proliferative vitreoretinopathy, which in turn may be caused by retinal folds [5].

Considering the high risk of intra- and postoperative complications after repeat vitreoretinal surgery, it is important to develop a non-invasive pathogenetic treatment for retinal folds that would minimize potential damage to the sensory retina.

Currently, laser technologies are being increasingly used for treating retinal pathology. Retinal grid laser photocoagulation with spots applied in the checkerboard pattern and spaced > 1 spot size apart is a popular technique for enhancing the structural support provided by Müller cells and improving retinal architecture by creating chorioretinal adhesions. Active and sustainable retinal tissue regeneration can be achieved through micropulse laser therapy [14, 15]. Below we report the use of combination laser therapy for the macular retinal fold developing in the late postoperative period after surgical RRD repair.

Clinical case

In October 2020, a male patient presented with complaints of metamorphopsia and diminished visual acuity in the right eye at the Research Center of Ophthalmology, Pirogov Russian National Research Medical University. According to his medical records, in August 2020 the patient had undergone microinvasive subtotal vitrectomy with intravitreal perfluorocarbon liquid (PFCL)/gas injection and received an intraocular lens implant for RRD in the right eye.

Once admitted to the Center, the patient underwent a comprehensive ophthalmic examination. Standard diagnostic tests included visometry for uncorrected visual acuity (UVA) and best corrected visual acuity (BCVA) and indirect ophthalmoscopy with a MaxField indirect lens (Ocular Inc.; USA). In addition, optical coherence tomography was performed using a Spectralis HRA+OCT platform (Heidelberg Engineering GmbH.; Germany).

Laser photocoagulation therapy was delivered using a VISULAS Trion work laser station (Carl Zeiss; Germany) operated at 577 nm wavelength.

During the initial examination the patient complained of metamorphopsia and diminished visual acuity in his right eye. UVA of the right eye (OD) was 0.05; BCVA was 0.7 for OD and 1.0 for the left eye (OS).

Ophthalmic OD biomicroscopy revealed that the anterior segment was intact and the intraocular lens was well centered. The optic disc was pale pink, with well-defined margins. A PFCL bubble was visible peripapillarily on the nasal side. Pronounced retinal folding ending with a subretinal PFCL bubble extended from the temporal optic disc margin toward the 8 o’clock plane (fig. 1). The caliber of the retinal vessels was unchanged. Cellophane maculopathy also known as epiretinal membrane was visualized paravasally along the course of the superior and inferior temporal arcades. Laser-sealed retinal breaks were present in the upper quadrant of the peripheral

Of all OCT images of the right eye, the most informative in terms of postoperative dynamics were scan А (fig. 2А) and the next scan B passing 250 µm higher, closer to fovea (fig. 2B).

Considering the patient’s complaints, his medical history and the results of the comprehensive ophthalmic examination, the following diagnosis was established: operated RRD in the right eye complicated with macular retinal folding; epiretinal membrane; avitria; artiphakia.

In December 2020, a decision was made to perform laser microsurgery on the patient in order to restore the architecture of the macular zone, flatten the folds, and improve the morphology and function of the retina. The combination treatment was delivered in several steps. In the first step, the patient underwent grid laser photocoagulation. The burns were applied along the course of the retinal fold and under it in the checkerboard pattern in 3 to 4 rows depending on the severity of the fold; the avascular zone was avoided. The laser workstation was operated at the lowest possible settings to ensure the lowest intensity of coagulation: power 50 mW, pulse duration 0.05 s, spot diameter 100 µm, wavelength 577 nm, spacing 150 µm. Single laser spots were applied paramacularly along the upper edge of the macula. Additionally, laser coagulation was performed on the epiretinal membrane along the course of the superior and inferior temporal vascular arcades. In the second step, the patient received 3 sessions of micropulse laser therapy (wavelength 577 nm, burst duration 30 ms, micropulse duration 50 µs, pulse ratio 4.7%, spot diameter 100 µm, power 50 mW.

Two months after surgery, the comprehensive ophthalmic examination revealed a slight improvement, although no significant morphological and functional changes were observed.

Four months after the intervention, the patient reported a significant reduction of metamorphopsia. His UVA and BCVA had improved to 0.2 and 0.7, respectively. Ophthalmic biomicroscopy of the right eye revealed the intact anterior segment and the well-centered intraocular lens. The fold in the central zone had flattened and was now 921 µm wide (fig. 3B). Paramacularly and along the retinal fold, weakly pigmented coagulation spots were visible. The caliber of the retinal vessels was unchanged. Paravasally, weakly pigmented coagulation spots were present in the epiretinal membrane area. Changes in the retina can be clearly seen on the follow-up OCT scans (fig. 3A, B).

Six months later on another follow-up examination the patient reported the absence of metamorphopsias in the right eye; UVA: 0.2; BCVA: 0.7. On ophthalmic biomicrosopy the anterior segment was intact, the intraocular lens was wellcentered. The optic disc was pale pink, with well-defined margins. The retinal folds had unfolded, the dominant retinal fold was not visualized. A slight undulation (up to 1.371 µm in width) was visualized on the retinal surface where retinal folding had been previously observed (fig. 4B). Weakly pigmented coagulations spots were present in the epiretinal membrane area, except for the avascular zone. Changes in the retina can be clearly seen on the follow-up OCT scans (fig. 4A, B).

Clinical case discussion

Retinal folds are a clinically important complication of surgical RRD repair. Few attempts have been reported to surgically treat retinal folds, including macular folds of different etiology [2, 16, 18]. There is no clear guidance on the timeframe and indications for repeat surgery. Experiments conducted in vivo have demonstrated that apoptosis of the photoreceptor layer and thinning of the outer nuclear layer start a week after macular translocation [18].

Repeat surgery is often delayed because retinal folds can be diagnosed no sooner than gas injected in the vitreous cavity is reabsorbed. Another reason is the risk of complications in the early postoperative period, including hemophthalmia, inflammation, secondary glaucoma, cataracts, RRD recurrence, macular tears, retinal vascular occlusion, etc. [11, 17, 19].

This study describes an alternative to vitreoretinal surgery: a combination laser therapy involving 2 interventions with different mechanisms of action. The proposed treatment method has indisputable advantages like non-invasiveness, low injury rate, and lack of serious complications or adverse effects. Due to the gradual topographically directed effect of grid laser photocoagulation, we were able to unfold the retina, restore the position of the macula and its functional and morphological characteristics. Paramacular tissues (the dominant retinal fold) flattened out, and retinal thickness and structural organization were recovered. The macular profile shifted to its normal microtopographic position, becoming more clearly visible on OCT scan B (fig. 3B); foveal depth and width also normalized. The patient’s metamorphopsia (distorted vision) resolved, his uncorrected visual acuity and the ability to use binocular vision improved. In addition, micropulse laser therapy prolonged tissue regeneration.

Summing up, the coagulation effect of laser energy applied locally to achieve controlled retinal stretching causes shifting of retinal microlayers, reorganizing the architecture of the macular zone. Low-dose exposure of the affected retinal zones to micropulse laser energy activates prolonged regeneration.

The proposed method produced pronounced morphofunctional effects on macular retinal folding, which develops in the late postoperative period after retinal detachment repair.

Conclusion

The proposed combination laser treatment of macular folds developing in the late postoperative period after RRD repair significantly improved the morphofunctional characteristics of the eye. The application of transpupillary laser surgery to ophthalmological practice broadens the arsenal of methods for noninvasive correction of RRD associated with macular retinal folds

The study demonstrates the potential of laser microsurgery (at the micron level) for correcting the damaged microtopography and microarchitecture of the macular retina, ensuring recovery of normal functions of the eye.