Volume 57 · Issue 02 · 2021

It has been recently recognized that biomechanics plays a crucial role in medicine. Corneal biomechanics is closely related to multiple aspects of corneal refractive surgery, such as indications for refractive surgery, choice of surgical methods, design of surgical parameters, management of surgical complications, prediction of surgical correction effect and long-term stability. By analyzing the various roles of biomechanics in corneal refractive surgery, this article aims to emphasize the possible influence of mechanics on corneal tissue, as well as the importance of biomechanics in corneal refractive surgery, so as to further improve the surgical safety, efficacy and predictability. (Chin J Ophthalmol, 2021, 57: 81-85)

With the improvement of intraocular lens materials and function design, phakic intraocular lens implantation has been widely carried out for myopia and astigmatism and achieved satisfactory clinical results at home and abroad. The range of corrected myopia diopters has gradually changed from previous super-high and high myopia to low myopia. With the expansion of the scope of indications and applications, it is necessary to strengthen the standardization of phakic intraocular lens implantation for myopia and astigmatism, and it is particularly important to further improve its safety and quality control. This article discusses how to rationally select indications, increase the accuracy of the design, and effectively prevent surgical complications, providing a reference for further improvement of clinical safety and quality control. (Chin J Ophthalmol, 2021, 57: 86-89)

Neurotrophic keratitis is a degenerative disease of the cornea caused by impairment in the trigeminal nerve, which can lead to dry eyes, corneal epithelial defects and corneal ulcers. The common causes include herpes virus infection, craniocerebral and ophthalmic surgery injury, and diabetes. Due to the reduced or lack of corneal sensitivity, patients′ symptoms are mild, while severe corneal stroma melting or even perforation may occur. And the conventional symptomatic treatment is not effective. In view of the current lack of clinical understanding of this disease, there are a large number of problems of misdiagnosis and mistreatment. To improve the level of diagnosis and treatment, the consensus of experts on diagnosis and treatment of neurotrophic keratitis, which can be used as a reference for ophthalmologists in clinical work, is formulated by the Cornea Group of Chinese Ophthalmological Society. (Chin J Ophthalmol, 2021, 57:90-94)

Limbal stem cell deficiency is an ocular surface disease with the imbalance of corneal epithelial homeostasis caused by decrease of number or weakening of function of limbal stem cells. In 2019 and 2020, the international limbal stem cell deficiency working group developed and released the international consensus on the definition, classification, diagnosis, staging and management of limbal stem cell deficiency, which provided a standard protocol for related research and clinical diagnosis and treatment of limbal stem cell deficiency. In order to help Chinese ophthalmologists to properly understand its core components, there is a need to make in-depth interpretation to the key and difficult contents of the international consensus. (Chin J Ophthalmol, 2021, 57: 95-99)

Questions and different opinions about the use of "complications" and "comorbidities" in "Comparison of long-term prognosis of different surgical approaches for the treatment of binocular congenital cataract in infancy" were raised, and discussed with the authors of the article.(Chinese Journal of Ophthalmology, 2021, 57:100-101)

Answers to the questions and discussions about the use of "complications" and "comorbidities" raised in "Discussion on the Comparison of Long-term Prognosis of Different Surgical Approaches in the Treatment of Congenital Cataract in Infancy", so as to indicate the different meanings of the Chinese expressions of the two nouns and the corresponding usage methods and situations, so as to more accurately express the objective facts in clinical practice.(Chinese Journal of Ophthalmology, 2021, 57:102-103)

To explore the rule of corneal biomechanical alteration with residual stromal thickness (RST) and percent tissue altered (PTA) after small incision lenticule extraction (SMILE) and to determine the factors influencing postoperative corneal biomechanical properties.

In this retrospective study, a total of 184 patients (184 right eyes) who underwent SMILE in Tianjin Eye Hospital Refractive Surgery Center from January 2019 to January 2020 were enrolled. There were 83 males and 101 females with age of (24.6±5.8) years. Corneal biomechanical parameters, including DA ratio, stiffness parameter at the first applanation (SPA1) and integrated radius (IR), were measured with Corvis ST preoperatively and at 3 months postoperatively. The association between PTA, RST and the changes of DA ratio, SPA1 and IR was assessed by linear and nonlinear regression analyses. Stepwise multivariate regression analyses were conducted to explore the factors associated with postoperative corneal biomechanical parameters with age, sex, anterior mean keratometry, spherical equivalent, postoperative central corneal thickness (CCT) and preoperative corneal biomechanical parameters as covariates. Preoperative and postoperative data were compared using the paired t test. Correlations were determined by the Pearson or Spearman analysis.

The alterations at 3 months postoperatively of DA ratio, SPA1 and IR were 1.33 (30.0%), 28.05 (26.0%) and 2.56 (34.0%), respectively. The changes before and after surgery were statistically significant (t=35.52, -28.00, 36.95, P<0.01). The best-fit curve showed that the changes of DA ratio, SPA1 and IR increased with the decrease of RST or increase of PTA. When the RST was<280 μm or the PTA was>28%, the slope of the change of DA ratio curve was significantly increased. Multivariate regression models showed that the factors with the greatest influence on postoperative DA ratio, SPA1 and IR were preoperative DA ratio (Sβ=0.489,P<0.01), preoperative SPA1 (Sβ=0.483,P<0.01) and preoperative IR (Sβ=0.471,P<0.01), respectively. The CCT was the second factor that influenced postoperative DA ratio and SPA1 (Sβ=-0.238,P<0.01; Sβ=0.326,P<0.01).

The changes of DA ratio, SPA1 and IR following SMILE increased with the decrease of RST or increase of PTA. With the RST<280 μm or the PTA>28%, the alteration of DA ratio significantly accelerated. Preoperative corneal biomechanical properties and postoperative CCT were main factors influencing corneal biomechanical properties after SMILE.(Chin J Ophthalmol, 2021, 57: 104-112)

To investigate the effects of implantable Collamer lens (ICL) with a central hole on the accommodative function of patients with high myopia at different ages after implantation.

A retrospective cohort study was conducted on 75 patients (150 eyes, 23 men and 52 women) with high myopia who underwent ICL implantation in Department of Ophthalmology of First Affiliated Hospital of Army Medical University from January 2017 to December 2018. The age was (28.99±7.26) years (range, 18-48 years). Forty patients (80 eyes) aged 18-34 years were included in the younger group and 35 patients (70 eyes) aged 35-48 years were included in the elderly group. To compare the changes and differences of accommodative function between the two groups, the uncorrected visual acuity, best corrected visual acuity, spherical equivalent error, amplitude of accommodation (AMP), negative relative accommodation (NRA), positive relative accommodation, single and both eyes′ accommodation of facility (AF), fused cross cylinder, near and far distance horizontal phoria, accommodative convergence/accommodation and visual satisfaction questionnaire before surgery and at 1, 3, 6 and 12 months after surgery were analyzed. ANOVA for repeated design, LSD, unpaired sample t-test, Paired t-test, Chi-square test and Fisher′s exact test were used for data analyses.

At each time point before and after operation, there were significant differences between the two groups in the AMP (F=16.511, P<0.05). The AMP of the younger group increased from (8.88±2.27) D at baseline to (9.51±1.34) D at 12 months, while it was decreased in the elderly group from (7.67±2.36) D at baseline to (6.56±2.63) D at 12 months. The trend of changes was significantly different (F=15.044,P<0.05). The AMP of the elderly group was significantly lower than that of the younger group at all time points (F=47.678, P<0.05). The NRA of the younger group was better than that of the elderly group (F=13.459, P<0.05), but the NRA had no significant changes in both groups postoperatively (F=1.788, P=0.141). We could not find any significant changes of positive relative accommodation between two groups (F=1.447, P=0.233). The monocular and binocular AF of two groups was increased significantly after surgery (F=34.296, 21.839, P<0.05). The AF of the younger group was better than that of the elderly group (F=80.327, 43.08, P<0.05). The fused cross cylinder was improved from baseline (0.12±0.32) D to (0.38±0.49) D at 12 months (F=4.752, P<0.05), while the difference was not found in the younger group (F=2.110, P=0.151). We could not find any significant changes of accommodative convergence/accommodation between two groups (F=0.389, P=0.505) or in each group (F=1.049, P=0.309) preoperatively and at 1, 3, 6 and 12 months after surgery.

ICL implantation is effective in the treatment of high myopia. The visual acuity, AMP, monocular and binocular AF may increase obviously. Big improvements in the accommodative function and high satisfaction of vision can be achieved, especially in younger patients. (Chin J Ophthalmol, 2021, 57: 113-121)

To compare the results of visual acuity testing for teenagers with visual acuity charts designed at 2.5-meter and 5-meter distances, and to investigate the accuracy of the 2.5-meter visual acuity chart.

It was a self-control study. A total of 227 teenagers (454 eyes) with ametropia who came to the ophthalmic clinic of Peking Union Medical College Hospital from March 2019 to September 2019 were included. There were 123 males and 104 females aged (11.74±3.26) years. The vision examiners were trained in the same testing environment and passed the consistency test. Distance visual acuity of all participants was tested with charts designed at 2.5 meters and 5 meters in a 10-minute interval. According to the age (7-9, 10-12, 13-15 and 16-18 years old) and visual acuity (1.00-0.52, 0.40-0.30 and 0.22-0.10), the results of two kinds of visual acuity charts were compared. The testing order of the two visual charts was randomly determined. The visual acuity results were converted into logMAR values and compared. Paried t-student test was used to compare the difference between two charts, and Pearson correlation test was used to explore the correlation between the results of two charts.

The visual acuity of the right eye was 0.37±0.24 (logMAR) at 2.5 meters and 0.50±0.26 (logMAR) at 5 meters. The distance visual acuity measured with the 2.5-meter visual acuity chart was better (t=16.19, P<0.01). The visual acuity of the left eye was 0.36±0.23 (logMAR) at 2.5 meters and 0.45±0.23 (logMAR) at 5 meters (t=11.71, P<0.01). The differences between two charts were larger among teenagers with lower visual acuity (r=0.387,P<0.01).

Under the same test conditions, the distance visual acuity measured with a 2.5-meter chart was significantly better than a 5-meter chart. The visual acuity chart designed at 2.5 meters was not an appropriate tool to measure distance vision in adolescents. (Chin J Ophthalmol, 2021, 57: 122-125)

To investigate the clinical characteristics and treatment of neurotrophic keratitis caused by trigeminal nerve injury.

Retrospective serial case study。Sixty-four patients (65 eyes) with NK due to trigeminal nerve injury admitted to Shandong Eye Hospital from January 2014 to June 2020 were collected, including 32 males (32 eyes) and 32 females (33 eyes), aged (57.5±12.9) years. The causes and clinical stages of the patients were analyzed, and the relationship between the causes and time of onset and the severity of corneal lesions, as well as the treatment methods and effects were observed.

The causes of the disease included brain tumor in 28 eyes (43.08%), postoperative trigeminal neuralgia in 13 eyes (20.00%), stroke in 12 eyes (18.46%), craniocerebral trauma in 5 eyes (7.69%), Guillain-Barre syndrome in 2 eyes (3.08%), and other causes in 5 eyes (7.69%) (all with facial nerve palsy). The course of the disease was 4 d to 10 years, of which 28 cases (29 eyes, 44.61%) had a course of ≤1 month, 25 cases (25 eyes, 38.46%) had a course of 1 to 6 months, and 11 cases (11 eyes, 16.92%) had a course of>6 months. All patients had significant corneal hypoesthesia. Twenty-seven eyes (41.54%) were complicated with exposure keratitis, of which 22 eyes were accompanied by facial nerve paralysis. According to Mackie's clinical stage, 1 eye (1.53%) in stage 1 showed dry tear film on the ocular surface, punctate roughness of corneal epithelium, obvious exposed area of palpebral fissure, and punctate staining in fluorescein sodium staining; Fourteen eyes (21.54%) in stage 2 showed epithelial defects in the central or inferior palpebral fissure of the cornea, mostly in horizontal oval shape, and the edges of epithelial defects were thickened and latently excavated; In stage 3, 50 eyes (76.92%) developed inferior central corneal ulcer and infiltration, with oval shape being the most common. Twelve eyes (18.46%) were co-infected. Fifty-nine eyes (90.76%) were treated with drug combined surgery, 16 eyes (27.12%) underwent permanent palpebral suture, 15 eyes (25.42%) underwent permanent palpebral suture combined with conjunctival flap covering, 21 eyes (35.59%) underwent permanent palpebral suture combined with amniotic membrane transplantation, 7 eyes (11.86%) underwent permanent palpebral suture combined with keratoplasty, and 6 eyes refused surgery due to systemic intolerance or personal reasons. Within six months after operation, 52 eyes (88.14%) were cured from 59 eyes (except 6 eyes who abandoned treatment and lost to follow-up), and the cure time was (10.52±6.52) d. Improved in 6 eyes (10.17%) and ineffective in 1 eye (1.69%).

Trigeminal nerve injury can cause patients' corneal perception to decrease or disappear significantly, resulting in unobvious symptoms and neglect of the condition. Clinical consultations are mostly stage 2 or 3 patients with severe corneal injury; In nearly half of the patients, keratitis occurred within 1 month after trigeminal nerve injury, which required drug combined with surgery. In order to cure ulcer and prevent corneal stromal melting, permanent palpebral suture was required。 (Chinese Journal of Ophthalmology, 2021, 57:126-132)

To identify the potential pathogenic variants in patients with congenital hereditary endothelial dystrophy (CHED).

A retrospective study. Six CHED patients were recruited from the Department of Ophthalmology at the Eye and ENT Hospital of Fudan University from August 2017 to September 2018. They were all males, and were 7 to 29 years old at the time of consultation, with an average age of 20.5 years. Whole-exome sequencing was performed on the six CHED patients. The Genome Analysis Tool Kit Best Practices pipeline and an in-house bioinformatics pipeline were applied for variants analyses, according to the 2015 American College of Medical Genetics and Genomics (ACMG) guidelines. Potential pathogenic variants were further validated by Sanger sequencing.

Six mutations in the SLC4A11 gene were identified in four out of six CHED patients, including four missense mutations (p.Arg869Cys, p.Pro773Leu, p.Arg869His, p.Arg755Trp), one frameshift mutation (p. Phe713fs), and one splicing site mutation (c.1330+1G>T). The frameshift mutation was pathogenic, while the pathogenicity of the splicing site mutation was unknown.

We identified six CHED-associated mutations in this study. The frameshift mutation (p. Phe713fs) and the splicing site mutation (c.1330+1G>T) were novel.(Chin J Ophthalmol, 2021, 57: 133-138)

A 34-year-old female presented to the doctor with chief complaint of redness in both eyes for 1 week. The slit lamp examination showed slight eyelid swelling, water-like discharge in the conjunctival sac of the lower eyelid, conjunctival follicles, gray-white pseudomembrane and small lamellar subconjunctival hemorrhage on the lower palpebral conjunctiva. Physical examination showed two erythematous macules(size 5 mm×6 mm) on the left palm. One erythematous macule(size 4 mm×5 mm) was seen on the right palm. Multiple erosions were located in the skin of upper and lower lips, oral cavity and the gingival mucosa. A diagnosis of hand, foot and mouth disease was made following by dermatological consultation. After topical antiviral and steroids treatment, the disease quickly relieved.(Chin J Ophthalmol, 2021, 57: 139-141)

The child was an 11-year-old male. When orthokeratology lens was fitted, corneal abnormalities were found for 1 day, and I went to the Department of Keratology, Beijing Tongren Eye Center, Beijing Tongren Hospital affiliated to Capital Medical University. Eye examination: visual acuity was 0.6 for the right eye and 0.8 for the left eye; There are many small patches of opacity in the elastic layer of the posterior cornea of the left eye, mainly distributed in the peripheral part of the cornea; Vesicles can be seen inside the opacified area, and the vesicles are more obvious after dilating the pupil by retinal reflection illumination (Quintessence Picture 1In a); A "double track" sign can be seen in the right eye (Quintessence Picture 1In B). Ocular examination of the father of the child: Scattered small patches of opacity were seen in the elastic layer of the posterior cornea of both eyes, and no "double track" sign was seen. OVOL2, COL8A2, ZEB1 and GRHL2 gene tests in children and their fathers were negative. Clinical diagnosis of the child: polymorphic corneal dystrophy in the posterior part of both eyes; Refractive error in both eyes.

Descemet′s membrane detachment (DMD) is a complication of intraocular surgery and is more likely to be seen after cataract surgery. As an intraoperative event, DMD usually features wrinkles and edema on the posterior corneal surface or floating membranoid substance seen in the anterior chamber. Such edema is often seen as surgery-caused corneal edema and membranoid substance as the anterior capsule of the lens. Thus, DMD is easily clinically ignored, even though it is conveniently treated if timely observed. Serious consequences are not uncommon with any delayed diagnosis or treatment. Risk factors include advanced age, previous corneal endothelial lesions and glaucoma, as well as preoperative shallow anterior chamber. Clinical diagnosis is based upon intraoperative judgment, corneal edema diagnosed under a microscope or slit lamp and consequent floating Descemet′s membrane. In serious cases, anterior segment OCT and UBM are required. Intracameral injections of air are traditionally adopted in the treatment. In less serious cases, patients see self-healing. (Chin J Ophthalmol, 2021, 57: 143-149)

Retinopathy of prematurity (ROP) has become the leading cause of childhood blindness worldwide. It is the key point of ROP prevention and treatment to screen out and deal with severe ROP that require treatment. However, more than 70% ROP regressed spontaneously without treatment. It is useful in deeply understanding the natural course of ROP and is helpful to develop strategies of ROP screening and prevention, that the characteristics of spontaneous regression of ROP are investigated comprehensively. The epidemic characteristics, clinical features, time course, related factors and visual impairment of ROP regression will be systematically summarized in this review.(Chin J Ophthalmol, 2021, 57: 150-155)

Recent studies have found that corneal biomechanical properties are closely related to the occurrence, development, diagnosis and treatment of some corneal diseases, and the effect of corneal surgery, which involves many professional concepts. This paper briefly summarizes the basic concepts, characteristics, measurement methods, influencing factors, application in the diagnosis and treatment of common eye diseases and its interventional treatment, aiming at promoting the understanding and mastery of corneal biomechanics by ophthalmologists, so as to improve the level of clinical diagnosis and treatment.(Chinese Journal of Ophthalmology, 2021, 57:156-160)