Recent advances in corneal neovascularization imaging.

Corneal neovascularization (CoNV) is a vision-threatening ocular disease commonly secondary to infectious, inflammatory, and traumatic etiologies. Slit lamp photography, in vivo confocal microscopy, angiography, and optical coherence tomography angiography (OCTA) are the primary diagnostic tools utilized in clinical practice to evaluate the vasculature of the ocular surface. However, there is currently a dearth of comprehensive literature that reviews the advancements in imaging technology for CoNV administration. Initially designed for retinal vascular imaging, OCTA has now been expanded to the anterior segment and has shown promising potential for imaging the conjunctiva, cornea, and iris. This expansion allows for the quantitative monitoring of the structural and functional changes associated with CoNV. In this review, we emphasize the impact of algorithm optimization in anterior segment-optical coherence tomography angiography (AS-OCTA) on the diagnostic efficacy of CoNV. Through the analysis of existing literature, animal model assessments are further reported to investigate its pathological mechanism and exhibit remarkable therapeutic interventions. In conclusion, AS-OCTA holds broad prospects and extensive potential for clinical diagnostics and research applications in CoNV.

An Eye into the Aorta: The Role of Extracellular Matrix Regulatory Genes ZNF469 and PRDM5, from Their Previous Association with Brittle Cornea Syndrome to Their Novel Association with Aortic and Arterial Aneurysmal Diseases.

The extracellular matrix is a complex network of proteins and other molecules that are essential for the support, integrity, and structure of cells and tissues within the human body. The genes ZNF469 and PRDM5 each produce extracellular-matrix-related proteins that, when mutated, have been shown to result in the development of brittle cornea syndrome. This dysfunction results from aberrant protein function resulting in extracellular matrix disruption. Our group recently identified and published the first known associations between variants in these genes and aortic/arterial aneurysms and dissection diseases. This paper delineates the proposed effects of mutated ZNF469 and PRDM5 on various essential extracellular matrix components, including various collagens, TGF-B, clusterin, thrombospondin, and HAPLN-1, and reviews our recent reports associating single-nucleotide variants to these genes' development of aneurysmal and dissection diseases.

The application of high-throughput sequencing technology in corneal diseases.

High-throughput sequencing technology, also known as next-generation sequencing technology, can explore new biomarkers and specific gene mutations. It has a pivotal role in promoting the gene research, which can limit the detection area, lessen the time needed for sequencing. Also, it can quickly screen out the suspected pathogenic genes of patients, gain the necessary genetic data, and provide the basis for clinical diagnosis and genetic counseling. In the research of corneal diseases, through the DNA sequencing of patients' diseased cells, it can provide a deeper understanding of corneal diseases and improve the diagnosis, classification and treatment alternatives of various corneal diseases. This article will introduce the application progress of high-throughput sequencing technology in corneal diseases, which will help to understand the application of this technology in various corneal diseases.

Mesenchymal Stem Cells and Exosomes: A Novel Therapeutic Approach for Corneal Diseases.

The cornea, with its delicate structure, is vulnerable to damage from physical, chemical, and genetic factors. Corneal transplantation, including penetrating and lamellar keratoplasties, can restore the functions of the cornea in cases of severe damage. However, the process of corneal transplantation presents considerable obstacles, including a shortage of available donors, the risk of severe graft rejection, and potentially life-threatening complications. Over the past few decades, mesenchymal stem cell (MSC) therapy has become a novel alternative approach to corneal regeneration. Numerous studies have demonstrated the potential of MSCs to differentiate into different corneal cell types, such as keratocytes, epithelial cells, and endothelial cells. MSCs are considered a suitable candidate for corneal regeneration because of their promising therapeutic perspective and beneficial properties. MSCs compromise unique immunomodulation, anti-angiogenesis, and anti-inflammatory properties and secrete various growth factors, thus promoting corneal reconstruction. These effects in corneal engineering are mediated by MSCs differentiating into different lineages and paracrine action via exosomes. Early studies have proven the roles of MSC-derived exosomes in corneal regeneration by reducing inflammation, inhibiting neovascularization, and angiogenesis, and by promoting cell proliferation. This review highlights the contribution of MSCs and MSC-derived exosomes, their current usage status to overcome corneal disease, and their potential to restore different corneal layers as novel therapeutic agents. It also discusses feasible future possibilities, applications, challenges, and opportunities for future research in this field.

Animal Models in Eye Research: Focus on Corneal Pathologies.

The eye is a complex sensory organ that enables visual perception of the world. The dysfunction of any of these tissues can impair vision. Conduction studies on laboratory animals are essential to ensure the safety of therapeutic products directly applied or injected into the eye to treat ocular diseases before eventually proceeding to clinical trials. Among these tissues, the cornea has unique homeostatic and regenerative mechanisms for maintaining transparency and refraction of external light, which are essential for vision. However, being the outermost tissue of the eye and directly exposed to the external environment, the cornea is particularly susceptible to injury and diseases. This review highlights the evidence for selecting appropriate animals to better understand and treat corneal diseases, which rank as the fifth leading cause of blindness worldwide. The development of reliable and human-relevant animal models is, therefore, a valuable research tool for understanding and translating fundamental mechanistic findings, as well as for assessing therapeutic potential in humans. First, this review emphasizes the unique characteristics of animal models used in ocular research. Subsequently, it discusses current animal models associated with human corneal pathologies, their utility in understanding ocular disease mechanisms, and their role as translational models for patients.

MicroRNAs Expression in Response to rhNGF in Epithelial Corneal Cells: Focus on Neurotrophin Signaling Pathway.

PURPOSE: Nerve growth factor efficacy was demonstrated for corneal lesions treatment, and recombinant human NGF (rhNGF) was approved for neurotrophic keratitis therapy. However, NGF-induced molecular responses in cornea are still largely unknown. We analyzed microRNAs expression in human epithelial corneal cells after time-dependent rhNGF treatment. METHODS: Nearly 700 microRNAs were analyzed by qRT-PCR. MicroRNAs showing significant expression differences were examined by DIANA-miRpath v.3.0 to identify target genes and pathways. Immunoblots were performed to preliminarily assess the strength of the in silico results. RESULTS: Twenty-one microRNAs (miR-26a-1-3p, miR-30d-3p, miR-27b-5p, miR-146a-5p, miR-362-5p, mir-550a-5p, mir-34a-3p, mir-1227-3p, mir-27a-5p, mir-222-5p, mir-151a-5p, miR-449a, let7c-5p, miR-337-5p, mir-29b-3p, miR-200b-3p, miR-141-3p, miR-671-3p, miR-324-5p, mir-411-3p, and mir-425-3p) were significantly regulated in response to rhNGF. In silico analysis evidenced interesting target genes and pathways, including that of neurotrophin, when analyzed in depth. Almost 80 unique target genes (e.g., PI3K, AKT, MAPK, KRAS, BRAF, RhoA, Cdc42, Rac1, Bax, Bcl2, FasL) were identified as being among those most involved in neurotrophin signaling and in controlling cell proliferation, growth, and apoptosis. AKT and RhoA immunoblots demonstrated congruence with microRNA expression, providing preliminary validation of in silico data. CONCLUSIONS: MicroRNA levels in response to rhNGF were for the first time analyzed in corneal cells. Novel insights about microRNAs, target genes, pathways modulation, and possible biological responses were provided. Importantly, given the putative role of microRNAs as biomarkers or therapeutic targets, our results make available data which might be potentially exploitable for clinical applications.

Genetics vs chronic corneal mechanical trauma in the etiology of keratoconus.

Both genetic and environmental factors have been considered to play a role in the etiology keratoconus. Eye rubbing, and more recently eye compression due to sleeping position, have been identified to be highly related to the condition, and are present in a high percentage of patients. Today, the predominant model is that these factors can provide the "second hit" necessary to generate the condition in a genetically susceptible individual. In addition, the extremely high prevalence in Arab populations, where endogamy could play a role, the high concordance rate in monozygotic twins, and the presence of family history of the condition between 5 and 23% of cases, support a genetic influence. Segregation analysis studies suggest that keratoconus is a complex non-Mendelian disease. Results from linkage analysis, next generation sequencing studies and genome-wide association studies also have suggested that genetic factors are involved in the condition. Recently, it has been proposed that mechanical trauma (i.e. eye rubbing or eye compression at night), is a sine quanon condition for the onset of keratoconus, and quite possibly its only cause. There are various arguments for and against this hypothesis. Indeed, it is possible, as initially suggested around 55 years ago, that the term "keratoconus" include diverse phenotypically similar conditions, which are actually of different etiology.

Expert consensus on the identification, diagnosis, and treatment of neurotrophic keratopathy.

BACKGROUND: Neurotrophic keratopathy (NK) is a relatively uncommon, underdiagnosed degenerative corneal disease that is caused by damage to the ophthalmic branch of the trigeminal nerve by conditions such as herpes simplex or zoster keratitis, intracranial space-occupying lesions, diabetes, or neurosurgical procedures. Over time, epithelial breakdown, corneal ulceration, corneal melting (thinning), perforation, and loss of vision may occur. The best opportunity to reverse ocular surface damage is in the earliest stage of NK. However, patients typically experience few symptoms and diagnosis is often delayed. Increased awareness of the causes of NK, consensus on when and how to screen for NK, and recommendations for how to treat NK are needed. METHODS: An 11-member expert panel used a validated methodology (a RAND/UCLA modified Delphi panel) to develop consensus on when to screen for and how best to diagnose and treat NK. Clinicians reviewed literature on the diagnosis and management of NK then rated a detailed set of 735 scenarios. In 646 scenarios, panelists rated whether a test of corneal sensitivity was warranted; in 20 scenarios, they considered the adequacy of specific tests and examinations to diagnose and stage NK; and in 69 scenarios, they rated the appropriateness of treatments for NK. Panelist ratings were used to develop clinical recommendations. RESULTS: There was agreement on 94% of scenarios. Based on this consensus, we present distinct circumstances when we strongly recommend or may consider a test for corneal sensitivity. We also present recommendations on the diagnostic tests to be performed in patients in whom NK is suspected and treatment options for NK. CONCLUSIONS: These expert recommendations should be validated with clinical data. The recommendations represent the consensus of experts, are informed by published literature and experience, and may improve outcomes by helping improve diagnosis and treatment of patients with NK.

Keratocyte biology.

The study of corneal stromal keratocytes is motivated by its strong association with corneal health and visual function. They play a dominant role in the maintenance of corneal homeostasis and transparency through the production of collagens, proteoglycans and corneal crystallins. Trauma-induced apoptosis of keratocytes and replacement by fibroblasts and myofibroblasts disrupt the stromal matrix organization, resulting in corneal haze formation and vision loss. It is, therefore, important to understand the biology and behaviours of keratocytes and the associated stromal cell types (like fibroblasts, myofibroblasts, stromal stem cells) in wound healing, corneal pathologies (including keratoconus, keratitis, endothelial disorders) as well as different ophthalmic situations (such as collagen crosslinking/photodynamic treatment, keratoplasty and refractive surgery, and topical medications). The recent development of ex vivo propagation of keratocytes and stromal stem cells, and their translational applications, either via stromal injection or incorporated in bioscaffold, have been shown to restore the corneal transparency and regenerate native stromal tissue in animal models of corneal haze and other disorders.

Visual rehabilitation of patients with corneal diseases.

BACKGROUND: Although most patients with visual impairment due to corneal diseases can be treated successfully with surgery, some require visual rehabilitation to restore reading ability. To evaluate the best LVAs especially in terms of reading speed and characterize this specific patient group we performed a prospective, randomized cross-over trial. METHODS: All 34 patients underwent a detailed examination (slit-lamp, funduscopy, SD-OCT, ETDRS) as screening. Only patients with corneal diseases without other ocular diseases were included. Reading-speed was assessed with International-Reading-Speed-Texts (IReST) consecutively with five different LVAs (low vision aids) during one day in a randomized cross-over design. Corneal haze was quantified with corneal densitometry (Pentacam). RESULTS: Patients were either visually impaired (n = 28), severely impaired (n = 4) or legally blind (n = 2). Patients read significantly faster with LVAs (p < 0.0001). Fastest reading speed could be achieved with video magnifier (CCTV). Optical magnifier and portable-electronic magnifier enabled significantly lower reading speeds (p < 0.01). In a subgroup of patients (VA < 3/60,n = 6) black background enabled patients to read significantly faster compared to white background (p = 0.03). CONCLUSION: Patients with low magnification requirement can be treated successfully with optical LVAs and portable-electronic magnifiers. More severely afflicted patients need a CCTV. Black background enables fastest reading-speeds, probably due to less blinding. Visual impairment can be estimated with corneal densitometry. Our trial confirms the capability of LVAs to successfully restore the reading ability in patients with corneal diseases, which is a crucial part of visual rehabilitation. TRIAL REGISTRATION: This trial was registered at the German Clinical Trials Register as DRKS00010887 at 09.08.2016.

[Problems and challenges in the development of keratoprosthesis surgery in China].

Keratoprosthesis implantation as an effective therapeutic method has been a treatment strategy in end-stage corneal blindness, contributing to restore vision and reduce the prevalence of blindness, but it has been restricted because of its high surgical technique and devastating complications. There are a large number of patients with corneal blindness in China, and the rate of high-risk or end-stage corneal blindness is high. It is of great significance to improve the understanding of the indications and contraindications of different kinds of keratoprostheses, as well as relevant technologies and knowledge, cope with the problems and challenges in the development period, and conduct safe and efficient clinical applications and related research, so that the technology of keratoprosthesis implantation in our country can go to the world steadily. (Chin J Ophthalmol, 2020, 56: 730-734).

[A summary of China's 70 years of development in diagnosis and treatment targeting corneal diseases].

Since the founding of the People's Republic of China, the diagnosis and treatment technology of corneal diseases has developed rapidly. In the field of infectious keratopathy, China was the first country that discovered chlamydia trachomatis in the world, which promoted the study on the pathogenesis as well as the diagnosis and treatment of infectious keratitis, especially fungal keratitis. In the aspect of surgical technology, we have learned from other countries and innovated different types of transplantation surgeries suitable for patients with corneal diseases in China. Regarding the construction of eye banks, the cornea donation process and the operation techniques have been developed and standardized. In addition, to improve the cornea disease-related inspection level, new equipment such as specular microscopy and confocal microscopy has been introduced. These efforts have decreased corneal diseases from the first blinding eye disease to the second in our country. In the past 70 years, China's diagnosis and treatment technology in corneal diseases has achieved remarkable progresses, but there are still many shortcomings. Standing on the shoulders of the older generations of ophthalmologists, we should continue to serve the patients with corneal diseases wholeheartedly. We would like to send congratulations on the 70th anniversary of Chinese Journal of Ophthalmology with this article. ( Chin J Ophthalmol, 2020, 56: 401-408).

[Observation and quantification of diabetic keratopathy in type 2 diabetes patients using in vivo laser confocal microscopy].

Objective: To study the diabetic keratopathy in type 2 diabetes patients with retinopathy by in vivo laser confocal microscopy. Methods: This was a case-control study. Ninety type 2 diabetes patients were involved in this study from May 2015 to December 2019 in Qingdao Eye Hospital. According to the diabetic retinopathy clinical stage, these patients were divided into the non-proliferative diabetic retinopathy (NPDR) group (30 cases), early stage proliferative diabetic retinopathy (PDR) group (30 cases) and intermediate to late stage PDR group (30 cases). Thirty non-diabetic healthy volunteers were included in the control group. The central cornea was observed with an in vivo laser confocal microscope. The corneal nerve fiber density, nerve fiber length, nerve branch density, and nerve fiber tortuosity were compared between groups. The corneal Langerhans cells, epithelial cells, stromal cells and endothelial cells were also compared. Results: There were more nerve fibers and branches in the control group than the other three diabetic groups. The nerve fiber length in the control group, NPDR group, early stage PDR group and intermediate to late stage PDR group was (21.55±2.57), (14.73±1.56), (11.23±1.40) and (8.02±1.33) mm/mm2, respectively, and there were statistically significant differences between the groups (F=316.17, P=0.00). In the nerve fiber density, nerve branch density and curvature, there were statistically significant differences between the groups (F=345.72, 479.46, 167.00, all P=0.00). The basal cell density in the control group, NPDR group, and two PDR groups was (5 761±303), (5 336±367), (4 146±379) and (3 658±365) cells/mm2, respectively, and there were statistically significant differences between the groups (F=234.94, P=0.00). The anterior stromal cell density in the four groups was (836±30), (727±57), (544±59) and (360±47) cells/mm2, respectively, and there were statistically significant differences between the groups (F=535.08, P=0.00). The hexagonal endothelium cell rate in the four groups was 62.0%±5.5%, 51.1%±3.7%, 40.2%±4.0% and 27.8%±3.9%, respectively, and the Langerhans cell density was (1.5±0.6), (4.2±1.3), (6.8±2.1) and (10.9±2.1) cells/mm2, respectively; there were statistically significant differences between the groups (F=342.28, 179.78, all P=0.00). There was no statistically significant difference between the groups in the corneal endothelial cell density (F=1.58, P=0.20). Conclusions: In type 2 diabetes patients with diabetic retinopathy, the corneal nerve fiber and branch density can be significantly reduced, and the density of the hexagonal corneal endothelial cells, epithelial basal cells and anterior stromal cells can also decrease. Langerhans cells may be involved in the development diabetic keratopathy. (Chin J Ophthalmol, 2020, 56: 754-760).

[Research progress on limbal stem cell transplantation].

Limbal Stem Cell Deficiency (LSCD) is an ocular surface disease caused by the decrease of the quantity and dysfunction of limbal stem cell, which is characterized by conjunctivalization and other signs of epithelial dysfunction. For sever LSCD, surgery is the main treatment way. Recently, plenty of researches published the outcomes of different operation methods. This article summarized five major operations, including conjunctival limbal autograft (CLAU), simple limbal epithelial transplantation (SLET), limbal allograft, cultivated limbal stem cell transplantation (CLET) and cultivated oral mucosal epithelial transplantation (COMET). (Chin J Ophthalmol, 2020, 56:956-960).

[New progress in the reuse of human corneal stromal lenticules from SMILE].

With the extensive development of small incision lenticule extraction (SMILE), a large number of human corneal stromal lenticules were extracted integrally during the operation, which led some experts to study the reuse of the lenticules. In experimental research, the lenticules were used to culture fibroblasts, construct corneal scaffolds and describe the biomechanical behaviors of cornea by cytobiology, immunology and biomechanics. In clinical study, the lenticules had been successfully reimplanted into autologous or allogenic cornea of human subjects for correcting hyperopia and presbyopic, patching corneal perforation and treating defective keratopathy and so on. (Chin J Ophthalmol, 2020, 56:144-148).

[Transplantation of endothelium and Descemet's membrane]. / Transplantatsiia éndoteliia i destsemetovoi membrany.

Nowadays, endothelial keratoplasty has become an alternative to penetrating keratoplasty (PKP) in the management of corneal endothelial dysfunction. Descemet membrane endothelial keratoplasty (DMEK) is a relatively new corneal transplantation surgery technique suited for patients with endothelial insufficiency, an increasing number of surgeons are learning the graft preparation technique and the surgery itself after seeing its excellent postoperative visual outcomes and faster rehabilitation of patients. DMEK has significant advantages in comparison with automated and manual Descemet Stripping Endothelial Keratoplasty (DSAEK/DSEK) and PKP including lower risk of immunologic graft rejection (1-2%), lower cost of the procedure, and it does not require expensive equipment such as a microkeratome or a femtosecond laser device. Another advantage is that the corneal graft tissue can be used for several recipients - e.g. when the Descemet's membrane and endothelium are used for a patient with endothelial dysfunction of the cornea, the retained stroma and epithelium can be then used for another patient with pathology of these corneal layers. Key problematic issues regarding this surgery are the technical difficulties during graft preparation and during surgery itself, however the majority of surgeons report very good results after gaining some experience. The article reviews latest clinical trials on DMEK and describes its strengths and weaknesses.

[Pre-descement membrane endothelial keratoplasty for treatment of patients with corneal endothelial decompensation].

Objective: To investigate the clinical outcomes of Pre-descement membrane endothelial keratoplasty (PDEK) for treatment of patients with corneal endothelial decompensation. Methods: Retrospective study of case series. The cases of 20 patients (20 eyes) who were diagnosed with corneal endothelial decompensation induced by various original diseases and received PDEK during July 2016 and December 2016 at Zhongshan Ophthalmic Center have been analyzed. The participants included 8 males and 12 females with an average age of (59.3±11.8) years. All 20 patients received PDEK operation, the Dua's layer, descement membrane and endothelium of donor tissue were separated from the underlying stroma with the application of big-bubble technique, and donor discs with diameters of 7.75 or 8.00 mm were harvested with scissors. The donor discs were stained with 0.06% trypan blue and loaded on inserters which were then gently inserted into the anterior chamber of the recipient. When the rolled inserted graft was unfolded, air was carefully injected into the anterior chamber underneath the graft so that the graft can attach to the stroma of the recipient. Post-operation follow-ups of over 6 months have been conducted for all patients, the best spectacle corrected visual acuity (BSCVA), the position of donor disc, corneal thickness and corneal endothelial cell density (ECD) were documented. The pre-operation and post-operation (6 months postoperatively) corneal thickness data of the patients were analyzed with paired sample t test. Results: The success rate of preparing PDMEK donor disc with big-bubble technique is 90% (18/20). Eighteen patients (90%) received PDMEK surgery successfully. Anterior segment optical coherence tomography (AS-OCT) results indicated that sixteen donor discs (16/18) were well attached to the back surface of the recipient stroma, and that two discs (2/18) dislocated at 6 days after surgery. At 6 months post-operatively, the corneas of 14 patients (14/18) turned clear with their BSCVA ranging 0.4 to 1.0, and the ECD was (1 389.3±373.2) cells/mm(2) for the patients with clear corneas. At 6 months post-operatively, the average corneal thickness of the patients reduced to (605±45) µm from the preoperative level of (655±56) µm, and the differences are of statistical significance (t=2.137, P=0.032). Conclusions: Application of big-bubble technique could effectively secure the success rate of PDEK disc preparation and control the loss of donated corneas. PDEK disc can be easily handled and unrolled in the anterior chamber, which could improve the postoperative clinical outcomes. (Chin J Ophthalmol, 2018, 54: 105-110).

[The research progress of relationship between advanced glycation end products and diabetic keratopathy].

Diabetic keratopathy is a common ocular complication of patients with a long-term history of diabetes and it will have a negative effect on the visual quality and function. A study reported that the incidence of diabetic keratopathy in diabetic patients ranged from 47% to 64%, but the precise underlying pathogenesis remains unclear. There is evidence that advanced glycation end products contribute substantially to the onset and progress of various diabetic complications and it is a key factor for the mechanism of the hyperglycemic memory. This review focuses primarily on the present research state and prospect of advanced glycation end products and their role in the pathological changes of the cornea. (Chin J Ophthalmol, 2018, 54: 475-480).

[Concerns on the diagnosis and treatment of corneal epitheliopathy].

Corneal epitheliopathy is a commonly seen disease in the clinical work. However, due to its complicated causes, there remain misdiagnosis and mistreatment, which would aggravate epithelial keratopathy and induce corneal scars, eventually leading to irreversible visual impairment. In this article, the primary and secondary causes of corneal epithelial lesions are described in detail. The classification, diagnosis and treatment principles of the disease are also presented to arouse more concern about corneal epitheliopathy. (Chin J Ophthalmol, 2017, 53: 161-163).

[Analysis of corneal complications in children wearing orthokeratology lenses at night].

Objective: To explore the characteristics, prognoses and corneal complications of children wearing orthokeratology lenses (Ortho-K) at night. Methods: Retrospective case analysis. A total of 113 cases (219 eyes) wore Ortho-K for myopia at night, including 7 cases with unilateral glass wear. The average age was (11.5±2.0) years old. The myopia ranged from -1.00 D to -9.00 D in all eyes and from -2.00 D to -4.00 D in 157 of them. Examinations were performed before lens wearing, at 1 hour, the next morning, 2 days, 3 days, 1 week and 2 weeks after lens wearing, and thereafter once a month. The follow-up was 6 months. Slit lamp examination was used to observe whether there was edema, mechanical damage, pigment deposition, turbidity or infiltration. The morphology, location, number, range and depth of fluorescein staining were tracked for more than 6 months. Results: There were punctate corneal epithelial exfoliation in 18 cases (29 eyes, 13.24%), corneal stromal infiltration and opacity in 5 cases (6 eyes, 2.74%), and corneal iron deposition in 9 cases (17 eyes, 7.76%), with no obvious symptoms. After stopping wearing lenses and related treatment, the punctate epithelial exfoliation was completely cured, and the other complications gradually disappeared within 6 months. These complications occurred within 3 months after lens wearing in six eyes and after at least 6 months of lens wearing in 46 eyes. Conclusions: Children who have complications after wearing Ortho-K at night should immediately stop wearing the lenses. Timely treatment and follow-up help to avoid deterioration and serious complications. Orthokeratology should be performed in medical institutions, with the follow-up by qualified ophthalmic doctors. (Chin J Ophthalmol, 2017, 53:198-202).