Subjects
We retrospectively reviewed 34 patients with unilateral lens subluxation recruited from the Department of Ophthalmology, Guangdong Provincial People’s Hospital, from December 2015 to December 2017. All patients were divided into two group, according to with or without acute angle closure attack history. Seventeen eyes of 17 patients with lens subluxation and acute angle closure and their fellow eyes were in the AAC group. Seventeen eyes of 17 patients merely with lens subluxation and their fellow eyes were served as the non-AAC group. An informed consent was obtained from each patient before surgery. This study was approved by the institutional Human Research Ethics Committee of Guangdong Provincial People’s Hospital and Guangdong Academy of Medical Sciences, Guangzhou, China and adhered to the tenets of the Declaration of Helsinki from the World Medical Association.
Inclusion criteria and exclusion criteria
Acute angle closure was defined as[6, 7]: 1) Presence of at least two of the following symptoms: ocular or periocular pain; nausea and/or vomiting; and a history of intermittent blurring of vision with haloes; 2) Presenting IOP higher than 21 mmHg in Goldmann applanation tonometry test; 3) Presence of at least three of following signs: conjunctival injection, corneal epithelial oedema, mid-dilated unreactive pupil, and shallow anterior chamber; 4) Presence of angle closure in the gonioscopy investigation. Patients with minimal to mild lens subluxation but without history or sign of previous acute angle closure were served as the non-AAC group.
Patients with following conditions were excluded: 1) Patients have been diagnosed with congenital diseases relating to lens subluxation, like the Marfan syndrome; 2) Patients have been definitely diagnosed as primary AAC; 3) Patients have clinically obvious or severe lens dislocation in the slit-lamp investigation; 4) Patients have undergone cataract surgery; 5) Patients are unable to cooperate with the ultrasound biomicroscopy (UBM) investigation. All patients received phacoemulsification operations and were followed up for 6 months.
Examinations and treatments
The degree of lens dislocation can be classified into 3 broad groups as described previously[8]: 1) Minimal to mild lens subluxation in which the lens edge uncovers 0% to 25% of the dilated pupil; 2) moderate lens subluxation in which the lens edge uncovers 25% to 50% of the dilated pupil; 3) severe lens subluxation in which the lens edge uncovers greater than 50% of the dilated pupil.
The medical histories were recorded for each patient. These histories included age, gender, family medical history, metabolic and genetic syndromes, ocular trauma, date of onset of symptoms, diagnosis, and treatments. All subjects underwent comprehensive ophthalmic examinations including assessment of Goldmann applanation tonometry, refraction tests, slit-lamp biomicroscopy, gonioscopy, dilated stereoscopic examination of the optic disc, and OCT (Spectralis OCT, Heidelberg Engineering, Germany). Uncorrected and corrected distance visual acuities (UDVA & CDVA) were measured using the Snellen chart in decimal values. Spherical equivalent (SE) was calculated as a sphere plus half of the cylinder power. Gonioscopy, performed in a dark room (with and without indentation), was performed in all participants by a single examiner (ZHY), who was masked to the UBM findings, using a Goldmann 2-mirror lens (Ocular Instruments Inc., Bellevue, WA, USA). The angle in each quadrant was graded based on the observed anatomical structures, following the modified Shaffer grading system[9, 10] (grade 0, no structure or Schwalbe’s line observed; grade 1, visible anterior nonpigmented TM; grade 2; visible posterior pigmented TM; grade 3, visible scleral spur; grade 4, visible ciliary body). Angle quadrants were considered as closed if they were grade 0 or 1. Gonioscopic angle closure in an eye was defined as closure in 2 or more quadrants[11]. Quantitative parameters of anterior segment including the angle opening distance at 500μm from the scleral spur (AOD500), anterior chamber depth (ACD), lens vault (LV), iris thickness at 750μm from the scleral spur (IT750), iris curvature (I-curve), and the status of the iris and zonules, were measured by the Ultrasound Biomicroscopy (UBM SW-3200L, Suoer Electrotec AG, China). In addition, axial length (AL) was measured by IOL Master (1322-734, Carl Zeiss Meditec AG, Germany). These procedures were performed by the same experienced ophthalmic technician (WJX). Qualitative UBM diagnoses were independently provided by two glaucoma ophthalmologists (HYZ and YJQ).
Preoperative IOL power calculations were performed using the AL and the keratometric readings measured by IOL Master. Phacoemulsification with capsular tension ring (CTR) and implantation of spherical IOLs with different diopters (Sensar AR40e, Abbott Medical Optics, CA, USA) were performed on those with 1 to 2 quadrants of zonular defect[12, 13]. In the present study, there were 17 affected eyes in the AAC group and 15 eyes in the non-AAC group that received phacoemulsification with subsequent implantation of the intraocular lens (IOL) and the capsular tension ring (CTR). All the surgeries were done by a single surgeon (HYZ) uneventfully. No complications were found in a 6-month follow-up.
Statistical analysis
Descriptive statistics were calculated for demographic characteristics of the AAC group and the non-AAC group. To compare the means between two groups, parametric variables were analysed by using Student t-test. Analyses of nonparametric variables were done by the Mann-Whitney test. A P-value less than 0.05 was considered as statistically significant. All analyses were conducted by using SPSS version 20.0 (SPSS Inc., Chicago, Illinois, USA).