Spike sign - To predict the formation of big bubble in deep anterior lamellar keratoplasty in advanced keratoconus.

Lamellar surgeries have revolutionized our understanding and practice of keratoplasties. However, the learning curve in deep anterior lamellar keratoplasty (DALK) makes it daunting for novice surgeons. This paper describes a unique intraoperative sign - the radial "spike sign," which heralds the commencement of a big bubble in some cases of advanced keratoconus in eyes that have not undergone any previous surgery. The spike sign was noted during big bubble DALK surgery and was then retrospectively looked for in recorded DALK surgical videos and correlated with the formation of a big bubble. The movement of air after injection was classified into the direct formation of a big bubble, stromal emphysema with no big bubble, and emphysema with the spike sign followed by a big bubble. In total, 104 surgical videos of big bubble attempts were evaluated and classified as such. The spike sign helps reduce the number of unnecessary attempts at big bubble formation during DALK, thus improving surgical outcomes.

Surgical and visual outcomes of flap repositioning for various flap-related pathologies post laser in-situ keratomileusis (LASIK).

To evaluate the surgical and visual outcomes of flap repositioning for various post-laser-assisted in-situ keratomileusis (LASIK) flap pathologies. Retrospective review of consecutive cases between April 1, 2017 and February 28, 2022, where surgical flap repositioning was performed following LASIK for various flap-related complications. Of the 6018 eyes, 31 needed flap repositioning (0.51%). Indications were flap displacement and folds in 20 eyes (64%), flap subluxation in five eyes (16%), epithelial ingrowth and interface debris in two each, and one eye each of diffuse lamellar keratitis and incomplete flap. Final best spectacle-corrected visual acuity of ≥ 20/25 was obtained in 25/31 (80%) eyes. The efficacy index pre to post repositioning showed significant improvement (0.86 ± 0.39 vs. 0.63 ± 0.29 preop, P = 0.011). Flap repositioning incidence was significantly higher (7/602 (1.16%)) during the COVID lockdown phases compared to the non-COVID lockdown phase (24/5416 (0.44%, P = 0.019)). The COVID group had lower efficacy (0.72 ± 0.36 vs. 0.90 ± 0.39, P = 0.300) and safety indices (0.85 ± 0.24 vs. 1.06 ± 0.35, P = 0.144) compared to the non-COVID group; however, the results were not statistically significant. The flap displacement rate was statistically higher in nasal hinged (microkeratome) flaps (18/2013, 0.89%) compared to superior hinged (Femto) flaps (13/4005, 0.32%) (0.32%, P = 0.003). Our study shows that flap repositioning has a low incidence in LASIK, with the most common indication being flap displacement/folds. The outcome post flap repositioning was poorer during the lockdown period, perhaps due to the inability to follow up early. Early identification and surgical repositioning are successful in both anatomical and visual restoration.

Impaired healing in an incision wound in corneal stroma in a lumican-null mouse.

PURPOSE: We investigated healing pattern of an incisional wound in corneal stroma of lumican-null (KO) mice. METHODS: C57BL/6 mice (wild-type, WT) and lumican-null (knockout, KO) mice were used. A linear full-thickness incision was produced in one cornea of each mouse. After intervals of healing, the corneas were processed for the following analyses. Histology was employed to measure the distance between each edge of the disrupted Descemet's membrane at the center of the cornea. Immunohistochemistry and real-time RT-PCR were employed to evaluate the expression of wound healing-related components in the tissue. Cultured ocular fibroblasts were obtained from cornea and sclera of WT and KO postnatal day 1 pups. The cells were subjected to examination for cell proliferation and expression of wound healing-related gene products. In vitro gel contraction assay was used to asses cell contractile activity of WT and KO cells. RESULTS: At day 5 of incision, the distance between the disrupted Descemet's membrane was larger in a KO mouse as compared with a WT mouse. Myofibroblast appearance in the wound was suppressed by the loss of lumican. The loss of lumican downregulated TGFß1's effects on mRNA expression of α-smooth muscle actin and collagen Ia1 in cultured ocular fibroblasts. Cell proliferation rate increased in injured stroma, which was further supported by in vitro datum of cell proliferation augmentation by the loss of lumican. Loss of lumican suppressed cell-mediated gel contraction. CONCLUSION: Loss of lumican perturbs the healing of penetrating incision in mouse corneal stroma in association with suppression of myofibroblast generation.

Collagen crosslinking impacts stromal wound healing and haze formation in a rabbit phototherapeutic keratectomy model.

Purpose: The purpose of this study was to evaluate the elastic modulus, keratocyte-fibroblast-myocyte transformation, and haze formation of the corneal stroma following combined phototherapeutic keratectomy (PTK) and epithelium-off UV-A/riboflavin corneal collagen crosslinking (CXL) using an in vivo rabbit model. Methods: Rabbits underwent PTK and CXL, PTK only, or CXL 35 days before PTK. Rebound tonometry, Fourier-domain optical coherence tomography, and ultrasound pachymetry were performed on days 7, 14, 21, 42, 70, and 90 post-operatively. Atomic force microscopy, histologic inflammation, and immunohistochemistry for α-smooth muscle actin (α-SMA) were assessed post-mortem. Results: Stromal haze formation following simultaneous PTK and CXL was significantly greater than in corneas that received PTK only and persisted for more than 90 days. No significant difference in stromal haze was noted between groups receiving simultaneous CXL and PTK and those receiving CXL before PTK. Stromal inflammation did not differ between groups at any time point, although the intensity of α-SMA over the number of nuclei was significantly greater at day 21 between groups receiving simultaneous CXL and PTK and those receiving CXL before PTK. The elastic modulus was significantly greater in corneas receiving simultaneous CXL and PTK compared with those receiving PTK alone. Conclusions: We showed that stromal haze formation and stromal stiffness is significantly increased following CXL, regardless of whether it is performed at or before the time of PTK. Further knowledge of the biophysical cues involved in determining corneal wound healing duration and outcomes will be important for understanding scarring following CXL and for the development of improved therapeutic options.

Glycosaminoglycans: Roles in wound healing, formation of corneal constructs and synthetic corneas.

Maintaining the clarity of the cornea is essential for vision, and is achieved through an exquisite array of collagen fibrils and proteoglycans in the corneal stroma. Alterations in the identity and modifications of the glycosaminoglycans (GAGs) are seen both throughout the normal wound healing process and in pathological conditions resulting in corneal opacity. Understanding these changes has been essential for the development of corneal prostheses and corneal reconstruction. The goal of this review article is to summarize and consolidate research in the alterations seen in glycosaminoglycans in injured and hypoxic states, address the role of proteins that can regulate glycosaminoglycans in the corneal wound healing process, and apply these findings to the context of corneal restoration through reconstruction or the insertion of synthetic devices.

Late-onset distal-apical intracorneal ring-segments keratopathy: an analysis of a large sample in a multicenter study.

PURPOSE: To review the prevalence and describe the characteristics, of cases with late-onset intracorneal ring segments (ICRS) keratopathy in a multicenter study. METHODS: A retrospective multicentric case-series study was performed in a specialized keratoconus service, from Buenos Aires, Argentina. An electronic clinical chart from patients with ICRS keratopathy between January 1999 and January 2019 was reviewed. We included cases with late-onset distal-apical ICRS keratopathy, which was defined as a persistent corneal lesion developed 12 months or later after implantation, located over, around, or closer to the ICRS. All the surgeries were performed by a manual corneal tunnel creation technique. Samples were taken to rule out infectious etiology. RESULTS: From 5217 eyes that underwent ICRS implantation, 13 cases (0.24%) were detected. The keratopathy onset was 72 ± 42.98 months (29-133) after ICRS implantation. Cultures were negative in all cases. An ICRS exchange was made for five cases in stage I and four in stage II. Four cases presented with partial ICRS extrusion in stage III. ICRS exchange was possible in two of them and a penetration keratoplasty was necessary for the rest. All cases remained stable 1 year after surgical procedures. CONCLUSIONS: A late-onset distal-apical ICRS keratopathy was detected with low prevalence (0.24%) in a large sample. It was classified into three stages according to its severity. Different treatments were selected for each stage, obtaining stable results 1 year after treatment.

An Efficient Technique for the Long-term Preservation of SMILE Lenticules Using Desiccation.

PURPOSE: To evaluate a desiccation protocol for the long-term preservation of human small incision lenticule extraction (SMILE) lenticules and to study their integration in an in vivo rabbit model. METHODS: Lenticules were retrieved after SMILE procedures in patients, then desiccated according to a novel protocol. Histologic and electron microscopic analyses were performed. Six rabbit eyes received grafts with an inlay technique, which consisted of inserting a desiccated lenticule into a stromal pocket. Rabbits were killed at different times between 6 and 24 weeks. Rabbit corneas were analyzed using optical coherence tomography, histology, and DAPI staining. RESULTS: Microscopic analysis of desiccated lenticules showed a preserved stromal architecture after rehydration. A decellularization of the lenticules after desiccation was observed without any chemical treatment. All rabbit corneas remained clear after grafting human lenticules and no rejection occurred. Optical coherence tomography showed regular lenticular implantation and no decrease in lenticule thickness. Histologic analysis showed no inflammatory infiltration around lenticules and no nuclear material inside lenticules after 6 months. CONCLUSIONS: A favorable integration of desiccated human SMILE lenticules in rabbit corneas was observed. The refractive issue of lenticular implantation must be investigated next. Clinical trials are needed to evaluate the use of desiccated SMILE lenticules to treat hyperopia or keratoconus in humans. [J Refract Surg. 2023;39(7):491-498.].

Birefringence analysis of collagen supraorganization in cat corneas with tropical keratopathy.

OBJECTIVE: To evaluate the birefringent properties of the cornea and examine the supraorganizational aspects of collagen fibers in cats with tropical keratopathy. PROCEDURE: In this study, 10-micrometer-thick sections of corneal tissue from cats with tropical keratopathy were examined, both in the opaque and transparent areas of the anterior stroma. Control samples were obtained from healthy cat corneas. Polarized light microscopy was employed to evaluate the birefringent properties using two distinct methods. The first method involved measuring the optical retardation associated with corneal birefringence, while the second method assessed the alignment/waviness of the birefringent collagen fibers. Differences were significant when p < .05. RESULTS: Tropical keratopathy resulted in a significant rise (p < .05) in optical retardation in both opaque and transparent regions of the cat cornea. In the anterior stroma, both the opaque zones and transparent tissue exhibited a higher degree of collagen fiber packing than the control corneas. However, no significant differences (p > .05) in alignment were observed between the transparent tissue of the diseased cornea and the healthy corneas. CONCLUSION: Supraorganizational changes in collagen fiber packing are not restricted to lesion zones in cat corneas affected by tropical keratopathy. Such alterations also occur in the corneal tissue of the anterior stroma adjoining the lesions. Therefore, it is plausible that the transparent tissue of the anterior stroma in corneas affected by the disease may have functional abnormalities, despite its macroscopic healthy appearance. Additional investigations are required to clarify the implications of these potential defects and their conceivable contribution to tropical keratopathy.

Standardization of corneal alkali burn methodology in rabbits.

Alkali burns are one of the most common injuries used in corneal wound healing studies. Investigators have used different conditions to produce corneal alkali injuries that have varied in sodium hydroxide concentration, application methods, and duration of exposure. A critical factor in the subsequent corneal healing responses, including myofibroblast generation and fibrosis localization, is whether, or not, Descemet's membrane and the endothelium are injured during the initial exposure. After exposures that produce injuries confined to the epithelium and stroma, anterior stromal myofibroblasts and fibrosis are typical, with sparing of the posterior stroma. However, if there is also injury to Descemet's membrane and the endothelium, then myofibroblast generation and fibrosis is noted full corneal thickness, with predilection to the most anterior and most posterior stroma and a tendency for relative sparring of the central stroma that is likely related to the availability of TGF beta from the tears, epithelium, and the aqueous humor. A method is described where a 5 mm diameter circle of Whatman #1 filter paper wetted with only 30 µL of alkali solution is applied for 15 s prior to profuse irrigation in rabbit corneas. When 0.6N, or lower, NaOH is used, then the injury, myofibroblasts, and fibrosis generation are limited to the epithelium and stroma. Use of 0.75N NaOH triggers injury to Descemet's membrane and the corneal endothelium with fibrosis throughout the stroma, but rare corneal neovascularization (CNV) and persistent epithelial defects (PED). Use of 1N NaOH with this method produces greater stromal fibrosis and increased likelihood that CNV and PED will occur in individual corneas.

Genipin increases extracellular matrix synthesis preventing corneal perforation.

PURPOSE: Corneal melting and perforation are feared sight-threatening complications of infections, autoimmune disease, and severe burns. Assess the use of genipin in treating stromal melt. METHODS: A model for corneal wound healing was created through epithelial debridement and mechanical burring to injure the corneal stromal matrix in adult mice. Murine corneas were then treated with varying concentrations of genipin, a natural occurring crosslinking agent, to investigate the effects that matrix crosslinking using genipin has in wound healing and scar formation. Genipin was used in patients with active corneal melting. RESULTS: Corneas treated with higher concentrations of genipin were found to develop denser stromal scarring in a mouse model. In human corneas, genipin promoted stromal synthesis and prevention of continuous melt. Genipin mechanisms of action create a favorable environment for upregulation of matrix synthesis and corneal scarring. CONCLUSION: Our data suggest that genipin increases matrix synthesis and inhibits the activation of latent transforming growth factor-ß. These findings are translated to patients with severe corneal melting.

Clinicopathological features of corneal invasion by filtering bleb.

PURPOSE: To describe the clinicopathological characteristics and explore the possible etiology of cornea invasion by filtering bleb (CIFB) after filtering surgery. METHODS: We reviewed 22 patients treated for CIFB between March 2005 and March 2022. The patients were followed up for more than 1 year. Slit-lamp examination, optical coherence tomography (OCT), ultrasound biomicroscopy, and histopathological examination were performed to observe the morphology of the bleb and depth of corneal invasion. Depending on the severity of the lesion, treatments consisting of local massage, acupuncture separation, or surgical resection were administered. RESULTS: The mean age of the patients was 56.3 ± 8.8 years. All patients underwent filtering surgery in the moderate or advanced stage of glaucoma. The filtering bleb was closely connected with the cornea, and its posterior boundary was locally adhered. Forward displacement of the internal opening of the filtering bleb was found in 4 of 7 surgically treated patients. OCT and pathological examination showed that the filtering blebs invaded the corneal stroma. Removal of the adhesion of the posterior boundary of the filtering bleb by different treatment methods successfully improved the patients' conditions. CONCLUSION: Filtering blebs can invade the corneal stroma. Adhesion of the posterior boundary and forward displacement of the internal opening of the filtering bleb are the possible causes of CIFB. Removal of the adhesion of the posterior boundary of the filtering bleb can halt the progression of CIFB.

Safety and efficacy of low-energy small incision lenticule extraction for the correction of myopia and myopic astigmatism: A retrospective analysis.

Purpose: To determine the safety and efficacy of low-energy settings in small incision lenticule extraction (SMILE) for correcting myopia and myopic astigmatism. Methods: We included patients aged ≥18 years with the myopia of -0.5 to -10 D and myopic astigmatism of -0.5 to -5 Dcyl in this retrospective case series performed at a private eye hospital in South India. All patients had preoperative best-corrected visual acuity of LogMar 0.0 ± 0, with stable refraction for 1 year and normal corneal topography. Ocular surface disease and other pathology cases were excluded. The repetition rate of the laser was 500 kHz, and the pulse energy was 110 nJ. The lenticule diameter was set at 6.5 mm, cap diameter was 7.20 mm, and intended cap thickness was 110-130 µ. The spot distance was 4.5 µm. All patients were evaluated immediately postoperation and on postoperative days 1, 8, and 30. Results: Overall, 541 eyes were included. The mean patient age was 25.03 ± 4.1 years. The mean spherical error was -3.76 ± 1.84 Ds. The mean cylinder was -1.24 ± 0.91. The mean spherical equivalent of refraction was -4.22 ±1.94 D. The logMAR on postoperative day 1 was 0.0 ± 0. The mean spherical equivalent at 1 month was 0.28 ± 1.06 D. There was no loss of Snellen's lines after the procedure. The mean spherical equivalent of refraction to the target was 95% within ± 0.50 D. The postoperative astigmatism was within 0.5 Dycl. No intraoperative complications of SMILE including retained lenticule fragments, tears of incision, or improper dissection occurred. Conclusion: Low-energy settings in SMILE are safe and effective in correcting myopia and myopic astigmatism including high cylinders (>3 Dcyl).

Bilateral interstitial keratitis in a patient with presumed brain tuberculoma.

Interstitial keratitis is an inflammation of the corneal stroma without epithelium or endothelium involvement. The underlying causes are mostly infectious or immune mediated. Brazil has one of the highest incidence rates of tuberculosis in the world. Tuberculosis is considered one of the causes of interstitial keratitis. Malnutrition and anemia are risk factors of the disseminated disease. This is a case report of a 10-year-old child who presented with decreased visual acuity and a clinical diagnosis of bilateral interstitial keratitis and sclero-uveitis. The patient had been treated with topical steroids with partial improvement. Examinations revealed severe iron deficiency anemia, negative serologies for human immunodeficiency virus and syphilis, positivity for cytomegalovirus- and herpes simplex-specific IgG, and purified protein derivative of 17 mm. During the follow-up, the patient presented with tonic-clonic seizures, and magnetic resonance imaging findings suggested a central nervous system tuberculoma. Interstitial keratitis improvement was observed after specific tuberculosis treatment. This is the first case report describing the association of interstitial keratitis and central nervous system tuberculoma.

Corneal scarring following collagen cross-linking: evidence of increased lysyl oxidase activity.

PURPOSE: To report a case of corneal scarring following collagen cross linking in a young female. METHODS: A 24-year-old female presented to us with complaints of decreased vision and a white spot in her left eye following collagen cross linking (CXL) performed elsewhere, four years prior. We diagnosed her as a case of left eye leucomatous corneal opacity for which she underwent optical penetrating keratoplasty under local anaesthesia. The excised corneal tissue was evaluated by routine histopathology and immunohistochemistry. RESULTS: At the final follow up visit, one year following corneal transplantation, her visual acuity improved to 20/20, J1 with a clear graft. CONCLUSION: Vision threatening corneal scarring may be rarely noted following CXL.

Corneal biomechanical stiffness and histopathological changes after in vivo repeated accelerated corneal cross-linking in cat eyes.

Corneal cross-linking (CXL) has been proved efficiency for treating progressive keratoconus and other corneal ectasia diseases by stabilizing corneal geometry and biomechanics. However, the necessity of repeated CXL treatment in patients is unknown. This study aimed to investigate corneal biomechanical stiffness and change in corneal histopathological characteristics after repeated accelerated CXL (A-CXL) in cat eyes. A-CXL was performed with 0.1% riboflavin applied for 10 min, followed by ultraviolet A irradiation at 30 mW/cm2 for 3 min at 365 nm in 15 domestic cats. Corneas (n = 30) were divided into three groups: one-time accelerated corneal cross-linking (A-CXL*1 group), repeated accelerated corneal cross-linking (A-CXL*2 group), and an untreated control group. In A-CXL*2 group, A-CXL was repeated at 1-month intervals. In vivo ocular examinations were performed pre- and postoperatively. Biomechanical analysis was performed using a biotester biaxial testing system. We used the Mooney-Rivlin strain-energy function to describe corneal material properties. No infection in any case after A-CXL was observed. Biomechanical tests showed that the stress-strain curves of the two A-CXL groups were significantly different from those of the control group (P < 0.01), whereas stress-strain curve of the A-CXL*2 group was similar to that of the A-CXL*1 group (P > 0.05). Delayed epithelial healing and haze were observed 1 month after surgery. Stromal demarcation line depth measured with anterior spectral-domain optical coherence tomography was 187.6 ± 20.4 and 197.1 ± 11.5 µm for the A-CXL*1 and A-CXL*2 groups, respectively (P > 0.05). These results show that A-CXL can increase corneal biomechanics in cat eyes. The biomechanical enhancement of cat corneas treated with repeated A-CXL at 1-month intervals was similar to that of performing a one-time A-CXL. Repeated cross-linking procedures at short intervals may increase the risk of adverse reactions, and more caution should be taken in clinical applications.

Full-field Optical Coherence Microscopy for Histology-like Analysis of Stromal Features in Corneal Grafts.

The quality of donor corneal stroma, which makes up about 90% of total corneal thickness, is likely to be one of the main, if not the major, limiting factor(s) for success of deep anterior lamellar and penetrating keratoplasty. These are surgical procedures that involve replacing part or all of the diseased corneal layers, respectively, by donated tissue, the graft, taken from a recently deceased individual. However, means to evaluate stromal quality of corneal grafts in eye banks are limited and lack the capability of high-resolution quantitative assessment of disease indicators. Full-field optical coherence microscopy (FF-OCM), permitting high-resolution 3D imaging of fresh or fixed ex vivo biological tissue samples, is a non-invasive technique well suited for donor cornea assessment. Here we describe a method for the qualitative and quantitative analysis of corneal stroma using FF-OCM. The protocol has been successfully applied to normal donor corneas and pathological corneal buttons, and can be used to identify healthy and pathologic features on both the macroscopic and microscopic level, thereby facilitating the detection of stromal disorders that could compromise the outcome of keratoplasty. By improving the graft quality control, this protocol has the potential to result in better selection (and rejection) of donor tissues and hence decreased graft failure.

[Mineral dysmetabolism in corneal diseases]. / Narusheniya mineral'nogo obmena pri zabolevaniyakh rogovitsy.

Functional status and biological properties of connective tissues significantly depend on the mineral elements involved in their metabolism. Connective tissue portion of the corneal stroma makes up most of its thickness; pathological changes in collagen fibers and the stroma can cause a range of corneal diseases, some of which are specifically associated with disorders of mineral metabolism. The article considers impairments of mineral metabolism as possible pathophysiological mechanisms in certain diseases and disorders of the cornea, and describes in detail the abnormalities associated with mineral dysmetabolism observed in patients with keratoconus.

Macular Corneal Dystrophy in an Adolescent Managed with Deep Anterior Lamellar Keratoplasty.

INTRODUCTION: Macular corneal dystrophy (MCD) is a rare autosomal recessive stromal dystrophy. The prevalence of inherited diseases varies in different communities. It is not commonly observed in Nepal. CASE: A 14-year male presented with bilateral gradual and painless blurred vision with photophobia of three years duration. Cornea of both eyes showed focal grayish opacities in anterior and mid stroma with intervening stromal haze. There was no history of consanguinity in the family. Anterior segment ocular coherence tomography showed thinning of cornea and deposits in corneal stroma. Macular corneal dystrophy was the clinical diagnosis and the patient underwent deep anterior lamellar keratoplasty in the right eye. Histopathological examination and histochemical staining with Alcian Blue supported the diagnosis. CONCLUSION: Significant improvement in vision was observed in the operated eye. MCD may be present in communities without evidence of consanguinity. It can cause visual impairment at an early age. Timely intervention improves vision and quality of life.

Fresh Human Myopic Lenticule Intrastromal Implantation for Keratoconus Using SMILE Surgery in a Long-term Follow-up Study: Ultrastructural Analysis by Transmission Electron Microscopy.

PURPOSE: To investigate new intrastromal histological structures that develop after myopic human lenticular implantation in keratoconus with femtosecond laser-assisted small incision lenticule extraction (SMILE) surgery using transmission electron microscopy. METHODS: Sixty eyes with advanced keratoconus indicated for corneal transplantation were included in this study. Fresh myopic lenticular implants were placed in all eyes through SMILE surgery. Lenticular implants were extracted from patients with myopic refractive errors of the cornea, untreated keratoconus, and treated keratoconus following 1, 2, and 3 years of surgery. These five lenticular samples were examined under the electron microscope and compared. RESULTS: Disorganized and thinned collagen fibers were observed in the stroma with degenerative stromal cells (telocyte-like cells and keratocytes) in the keratoconic cornea. Apoptotic bodies and cell debris were easily observed near the disorganized fibers. In contrast, the myopic refractive error of the control and treatment groups demonstrated well-organized parallel lamellar structures. Healthy keratocytes and telocyte-like cells were observed in samples obtained 1, 2, and 3 years after lenticular implantation. Thus, telocyte-like cells may be activated by appropriate stimuli, such as stem cells, and be involved in stromal regeneration. CONCLUSIONS: Fresh myopic intrastromal lenticular implantation is a safe, economical, and reliable technique that leads to increased corneal thickness, improved visual acuity, and the regeneration of healthy keratocytes and telocyte-like cells that are involved in stromal regeneration. [J Refract Surg. 2022;38(8):520-528.].

Late onset of a persistent, deep stromal and endothelial scarring after corneal collagen crosslinking for keratoconus: A case report.

INTRODUCTION: To report a late onset, deep stromal and endothelial corneal scar in a keratoconus patient after corneal collagen cross-linking (CXL). CASE DESCRIPTION: Observational case report. A 29-year-old man with bilateral keratoconus received an accelerated (A-CXL 10*9) epithelium-off CXL procedure in the left eye.6-months postoperatively, a 2.2 × 1.2 mm inferocentral corneal scar was detected, which was located in the posterior stroma ranging from approximately 350 µm until the endothelium, therefore was situated below the demarcation line. A topical corticosteroid treatment did not influence the magnitude or configuration of the scar. Visual acuity was never affected, which includes the examination 12 months postoperatively. CONCLUSIONS: We report a case of a late onset deep stromal and endothelial corneal scar 6 months after accelerated CXL as postoperative complication without affecting visual acuity.