Anterior Segment Features in Nanophthalmos With Secondary Chronic Angle Closure Glaucoma: An Ultrasound Biomicroscopy Study

Nanophthalmos-Associated MYRF gene mutation facilitates intraocular inflammation in mice

PURPOSE

Patients with nanophthalmos might be prone to developing intraocular inflammation following an acute glaucoma attack. Here, we aimed to investigate the role of MYRF in intraocular inflammation by modeling the mutation in mice.

METHODS

Nanophthalmos frameshift mutation of Myrf was introduced into the mouse genome with the CRISPR-Cas9 system. Signaling pathways in eye tissues were delineated using RNA sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Intraocular inflammation was induced by a lipopolysaccharide (LPS) intravitreal injection. Dexamethasone (DEX) was administered systemically and locally a week before the LPS injection. The anterior segment clinical scores of the mice were examined 24 h after the LPS injection. Infiltrating inflammatory cells were evaluated with histopathology and immunofluorescence. The mRNA levels of inflammatory cytokines were quantified with reverse transcription-quantitative PCR (RT-qPCR) and the corresponding protein concentrations using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Many inflammation-associated signaling pathways were enriched in Myrf mut/+ mice ocular tissues. Clinical scores of Myrf mut/+ mice were significantly higher than those of Myrf +/+ mice 24 h after LPS administration. Histological examination demonstrated high inflammatory cell infiltration in the anterior and vitreous chambers in Myrf mut/+ mice, with numerous CD45+ and CD11b+ inflammatory cells. Moreover, enhanced expression of inflammatory cytokines MCP-1, TGF-β, and IL-1β in eyes and aqueous humor of Myrf mut/+ mice was detected. Remarkably, pretreating Myrf mut/+ mice with DEX relieved the intraocular inflammation.

CONCLUSION

Nanophthalmos-associated MYRF mutation renders mouse eyes more susceptible to inflammation. Dexamethasone treatment ameliorates the inflammatory response.

Outcomes of Filtering Surgery Versus Clear Lens Extraction in Young Patients With Angle-Closure Glaucoma

PURPOSE

To compare the effect of filtering surgery versus clear lens extraction in young patients with medically uncontrolled angle-closure glaucoma (ACG).

DESIGN

Retrospective, nonrandomized, comparative, interventional study.

METHODS

We reviewed the medical charts of patients with the following scenarios: (1) age ≤40 years; (2) diagnosis of ACG without cataract, including primary angle-closure glaucoma (PACG), nanophthalmic ACG, and ACG combined with retinal dystrophies; and (3) ACG undergoing filtering surgery or clear lens extraction. The main outcomes including intraocular pressure (IOP), number of medications, best-corrected visual acuity, and severe complications were extracted at the postoperative early (within 1 week) and late stage (>3 months) follow-up.

RESULTS

Data from 160 eyes of 130 young patients with ACG were available. Eyes with 76 PACG, 12 nanophthalmic ACG, and 26 ACG with retinal diseases underwent filtering surgery, whereas eyes with 22 PACG, 12 nanophthalmic ACG, and 12 ACG with retinal diseases received clear lens extraction. Overall, filtering surgery and clear lens extraction resulted in significant but comparable IOP and drug reductions at the postoperative late stage in each ACG subgroup, with similar complete success rates between 2 treatments (all P > .05). Regarding the safety, filtering surgery and patients with retinal diseases were independent factors associated with postoperative malignant glaucoma (P < .05 in both multivariable logistic regression models).

CONCLUSIONS

This study highlights that the efficacy of clear lens extraction is comparable to that of filtering surgery in medically uncontrolled ACG in young patients, but clear lens extraction is safer, especially for young patients with ACG comorbid with retinal diseases.

Pathogenic variants of MFRP and PRSS56 genes are major causes of nanophthalmos in Japanese patients

BACKGROUND

Nanophthalmos (NNO) is a rare condition with significantly shorter axial length than normal. Several genes are known to cause NNO, among them the MFRP and PRSS56 genes have been reported to cause majority of NNOs. The purpose of this study was to determine the genetic basis of Japanese patients with NNO.

MATERIALS AND METHODS

We studied seven patients with NNO. Whole exome sequencing (WES) and Sanger sequencing were performed to determine the variants causing the NNO. We also reviewed the medical charts of the patients to determine the phenotype of these seven patients.

RESULTS

WES revealed that four patients from three families carried homozygous frameshift variants of the PRSS56 gene (c.1066dupC). Two novel variants of the MFRP gene were detected in the other two patients: one proband had a homozygous missense variant (c.1486 G>A) and the other had a compound heterozygous variant (c.1486 G>A and c.662_663insT). The axial length of the eight eyes with the PRSS56 variant was 15.69 ± 0.48 mm (mean ± SD) and that for the 4 eyes with the MFRP variant was 15.63 ± 0.69 mm. Three of the six cases with the PRSS56 or MFRP variant had the uveal effusion syndrome.

CONCLUSIONS

NNOs in Japanese patients are caused by variants of the PRSS56 and MFRP genes as in other ethnic populations. In addition, two new variants of the MFRP gene were found in our cohort. The phenotypes and anomalies in Japanese patients with NNO were similar to those reported for other ethnic populations.

Influence of Pilocarpine Eyedrops on the Ocular Biometric Parameters and Intraocular Lens Power Calculation

Objective

To evaluate the influence of pilocarpine eyedrops on the ocular biometric parameters and whether these parameter changes affect the intraocular lens (IOL) power calculation in patients with primary angle-closure glaucoma (PACG).

Methods

Twenty-two PACG patients and fifteen normal subjects were enrolled. Ocular biometric parameters including the axial length (AL), anterior chamber depth (ACD), lens thickness (LT), mean keratometry (Km), and white-to-white distance (WTW) were measured by using a Lenstar LS 900 device before and at least 30 minutes after instillation of 2% pilocarpine eyedrops. Lens position (LP) was calculated, and the IOL power prediction based on the ocular biometric parameters was performed using the Barrett Universal II, Haigis, Hoffer Q, Holladay I, or SRK/T formulas before and after pilocarpine application.

Results

In both PACG and normal groups, pilocarpine eyedrops induced a slight but statistically significant increase in the mean AL (0.01 mm for both groups) and mean LT (0.02 mm and 0.03 mm, respectively) but a significant decrease in the mean ACD (0.03 mm and 0.05 mm, respectively) and mean LP (0.02 mm and 0.04 mm, respectively). No significant changes in the mean Km and WTW were noticed in both groups. In addition, the IOL power calculation revealed insignificant changes before and after the pilocarpine instillation in both groups, regardless of the formula used.

Conclusions

Pilocarpine eyedrops can induce slight changes in the ocular biometric parameters including the AL, ACD, LT, and LP. However, these parameter changes will not result in a significant difference in IOL power estimation.

Incidence and characteristics of aqueous misdirection after glaucoma surgery in Chinese patients with primary angle-closure glaucoma

BACKGROUND

To report the incidence and clinical characteristics of aqueous misdirection (AM) after glaucoma surgery in Chinese patients with primary angle-closure glaucoma.

METHODS

Medical records of all patients diagnosed with primary angle-closure glaucoma who underwent glaucoma surgery in the Eye Hospital of Wenzhou Medical University between January 2012 and December 2021 were retrospectively reviewed. Cases of AM were identified through a keyword-based search. The incidence of AM was calculated. Demographic and clinical characteristics of the AM patients were also described.

RESULTS

A total of 5044 eyes with primary angle-closure glaucoma were included (mean age 65.81 ± 9.96 years, 68.11% women). Thirty-eight eyes developed AM, presenting an overall incidence of 0.75%. The mean time interval between surgery and first record of AM diagnosis was 2.57 ± 5.24 months (range, 0 day to 24 months). The incidence of AM was significantly higher in patients aged ≤ 40 years (21.28%) and those aged 40-50 years (3.32%), compared to those > 50 years (0.42%) (P < 0.001). AM developed much more frequently among patients with chronic angle-closure glaucoma (1.30%), compared to those with acute angle-closure glaucoma (0.32%, P < 0.001). Eleven eyes (0.37%) developed AM following non-filtering surgery compared to 24 eyes (2.27%) after filtering surgery (P < 0.001).

CONCLUSION

The incidence of AM after glaucoma surgery was 0.75% in Chinese patients with primary angle closure glaucoma. Younger age, chronic angle-closure glaucoma, and undergoing filtering surgery, were identified as associated risk factors for developing AM. Phacoemulsification may have less risk of developing AM compared to filtering surgery.

Cataract surgery in adult eyes with short axial length

PURPOSE OF REVIEW

Cataract surgery in eyes of patients with short axial length (AL) can be technically challenging and is associated with a high risk of intra- and postoperative complications. Several technical and surgical strategies have been proposed to optimize the visual outcome and decrease the rate of surgical complications and it is important to understand their applications in these cases.

RECENT FINDINGS

Traditional intraocular lens (IOL) measurement formulas in eyes with short AL have reduced reliability. Novel formulas such as the Kane formula provide a better refractive prediction. Surgery can be difficult in short eyes due to the crowdedness of the anterior chamber (AC) and the associated scleral abnormalities increasing the risk of uveal effusion. Surgical techniques such as prophylactic scleral incisions, limited pars plana anterior vitrectomy, and modified hydrodissection, have been shown to facilitate surgery in extremely short eyes and decrease the rate of operative complications. Although cataract surgery improves vision in these cases, short AL and shallow AC have been associated with worse visual outcomes.

SUMMARY

Newer 4 th generation IOL formulas have improved the refractive outcomes of cataract surgery in eyes with short AL. There are multiple evolving surgical strategies for optimizing surgery in these eyes. However, studies on the surgical and visual outcomes of cataract surgery in eyes with short AL are limited by their design and sample size. With further research and continued clinical experiences, we hope to develop evidence-based algorithms for the management of these complex cases.

Treatment of Nanophthalmos Cataracts: Surgery and Complications

PURPOSE

Cataract surgery in patients with nanophthalmos is complicated for ophthalmologists to perform. Due to the unique ocular anatomy, there is a high incidence of complex complications such as angle-closure glaucoma, fluid misdirection syndrome, and uveal effusion syndrome (UES) in the perioperative period of cataract surgery. This article will discuss the management options for cataract surgery in nanophthalmic eyes and complications.

METHODS

This review is searched through PubMed, focusing on articles published in the past 20 years. Articles were reviewed on the anatomical structure of nanophthalmic cataracts, the pathogenesis of complications, the selection of intraocular lenses, and surgical methods.

CONCLUSION

There is a strong correlation between abnormal ocular anatomy and complications in patients with nanophthalmos. Clinicians must not only select the appropriate intraocular lens formula based on the depth of the anterior chamber but also formulate personalized surgical methods based on its unique anatomical structure to avoid complications.

Ocular Biometry of Primary Angle-Closure Disease in Younger Patients

Background: The purpose of this study was to analyze the ocular biometric parameters of primary angle-closure disease (PACD) in younger patients and compare them with those of elderly patients. Methods: This clinic-based, cross-sectional study included 154 eyes of 154 patients with PACD, consisting of 77 eyes of patients aged 40 years or younger and 77 eyes of patients older than 40. The PACD case definition was compatible with the ISGEO definition. Anterior segment parameters were measured by ultrasound biomicroscopy, axial length (AL) and lens thickness (LT) were measured by A-scan ultrasonography measurements, and the thickness of the retina and choroid were measured by optical coherence tomography. The differences in ocular biometric parameters between different age groups were compared by independent sample t-tests or Mann-Whitney U tests, and the correlation between the parameters and age was analyzed. Results: Compared to older PACD patients, the lens vault(LV),LV/LT and subfoveal choroidal thickness (SFCT) of younger patients were larger, while the peripheral and mean iris thickness (IT), trabecular-ciliary angle (TCA), ciliary body thickness (CBT), AL and LT were smaller (all P < 0.01). There was no significant difference in anterior chamber depth, anterior chamber width, pupil diameter, angle opening distance at 500 μm from the scleral spur, anterior chamber angle and iris convexity between the two groups (all P > 0.05). AL, LT, IT, TCA and CBT were positively associated with age (all P < 0.001), while LV and SFCT were negatively associated with age (P = 0.027 and P < 0.001, respectively). Conclusions: Compared with elderly patients, younger PACD patients had more anteriorly positioned lenses, thinner and more anteriorly rotated ciliary bodies, thicker choroids, and shorter axial length. These characteristics might be important anatomical bases for the earlier onset of PACD and the higher risk of malignant glaucoma after filtering surgery.

Myelin regulatory factor deficiency is associated with the retinal photoreceptor defects in mice

Previously, we reported the myelin regulatory factor (MYRF) as a candidate gene for nanophthalmos. We have also produced Myrf knockdown (Myrf+/-) mouse strain to investigate the cellular and molecular phenotypes of reduced MYRF expression in the retina. Myrf+/- mouse strain was generated using the CRISPR/Cas9 system. Optomotor response system, electroretinogram (ERG), spectral-domain optical coherence tomography (SD-OCT), histology, and immunohistochemistry were performed to evaluate retinal spatial vision, electrophysiological function, retinal thickness, and pathological changes in cone or rod photoreceptors, respectively. RNA sequencing (RNA-seq) was performed to investigate the underlying molecular mechanism linking Myrf deficiency with photoreceptor defects. The genotype and phenotype of CRISPR/Cas9-induced Myrf+/- mice and their offspring were comprehensively investigated. Photoreceptor defects were detected in the retinas of Myrf+/- mice. Visual acuity and ERG responses were decreased in Myrf+/- mice compared with the control mice (Myrf+/+). The loss of cone and rod neurons was proportional to the decreased outer nuclear layer (ONL) thickness. Moreover, RNA-seq revealed that phototransduction and estrogen signaling pathways played important roles in the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Myrf+/- mouse strain provides a good model to investigate the function of the MYRF gene. Photoreceptor defects with impaired functions of spatial vision and retinal electrophysiology indicate an important role played by MYRF in retinal development. Alterations in phototransduction and estrogen signaling pathways play important roles in linking Myrf deficiency with retinal photoreceptor defects.

Nanophthalmos-Associated MYRF Gene Mutation Causes Ciliary Zonule Defects in Mice

Purpose

Patients with nanophthalmos who undergo intraocular surgery often present with abnormal ciliary zonules. In a previous study, we reported mutation in MYRF that is implicated in the pathogenesis of nanophthalmos. The aim of this study was to model the mutation in mice to explore the role of MYRF on zonule structure and its major molecular composition, including FBN1 and FBN2.

Methods

Human MYRF nanophthalmos frameshift mutation was generated in mouse using the CRISPR-Cas9 system. PCR and Sanger sequencing were used for genotype analysis of the mice model. Anterior chamber depth (ACD) was measured using hematoxylin and eosin–stained histology samples. Morphologic analysis of ciliary zonules was carried out using silver staining and immunofluorescence. Transcript and protein expression levels of MYRF, FBN1, and FBN2 in ciliary bodies were quantified using quantitative real-time PCR (qRT-PCR) and Western blot.

Results

A nanophthalmos frameshift mutation (c.789delC, p.N264fs) of MYRF in mice showed ocular phenotypes similar to those reported in patients with nanophthalmos. ACD was reduced in MYRF mutant mice (MYRF^mut/+) compared with that in littermate control mice (MYRF^+/+). In addition, the morphology of ciliary zonules showed reduced zonular fiber density and detectable structural dehiscence of zonular fibers. Furthermore, qRT-PCR analysis and Western blot showed a significant decrease in mRNA expression levels of MYRF, FBN1, and FBN2 in MYRF^mut/+ mice.

Conclusions

Changes in the structure and major molecular composition of ciliary zonules accompanied with shallowing anterior chamber were detected in MYRF^mut/+ mice. Therefore, MYRF mutant mice strain is a useful model for exploring pathogenesis of zonulopathy, which is almost elusive for basic researches due to lack of appropriate animal models.

Morphological features of anterior segment: factors influencing intraocular pressure after cataract surgery in nanophthalmos

Purpose

To investigate the anterior segment in nanophthalmic eyes and their association with intraocular pressure after cataract surgery.

Methods

Thirty-two nanophthalmic eyes (axial length [AL] < 18.5 mm) in 18 patients and 35 normal eyes (21 ≤ AL ≤ 24.5 mm) in 35 controls who had undergone uneventful cataract surgery were included. Swept-source optical coherence tomography was used to compare the anterior segment structures between the two groups. The associations between the anterior segment characteristics of nanophthalmic eyes and postoperative intraocular pressure (IOP) were also investigated.

Results

The IOP-lowering effect of cataract surgery was remarkably insufficient in nanophthalmic eyes. Peripheral anterior synechiae (PAS) were observed in 56% (18/32) of nanophthalmic eyes, and a characteristic boomerang-shaped iris was observed in 28% (9/32). The anterior surface of the iris seemed “smoother” in nanophthalmic eyes than in normal eyes. Schlemm’s canal (SC) diameter, SC area, trabecular meshwork (TM) thickness, TM width, and TM area were generally smaller in the nanophthalmic eyes. Younger age, higher preoperative IOP, broader PAS, and smaller SC area were main contributors to higher postoperative IOP. AL and SC diameter may also be of great importance in IOP prediction in patients without glaucoma surgery and PAS.

Conclusions

The morphological features of the anterior segment in nanophthalmic eyes are significantly different from those of normal eyes. Influencing factors such as age, AL, preoperative IOP, extent of PAS, SC and TM size could all be prognostic for IOP after cataract surgery in nanophthalmic eyes.

Trial registration

ClinicalTrails.gov, Trial registration number: NCT02182921, Registered 8 July 2014.

The Pathogenesis and Treatment of Complications in Nanophthalmos

Microphthalmos is a type of developmental disorder ophthalmopathy, which can occur isolated or combined with other ocular malformations and can occur secondary to a systemic syndrome. Nanophthalmos is one of the clinical phenotypes of microphthalmos. Due to the special and complex structure of nanophthalmic eyes, the disorder is often associated with many complications, including high hyperopia, angle-closure glaucoma, and uveal effusion syndrome. The management of these complications is challenging, and conventional therapeutic methods are often ineffective in treating them. The purpose of this paper was to review the concept of nanophthalmos and present the latest progress in the study of the pathogenesis and treatment of its complications. As it is considerably challenging for ophthalmologists to prevent or treat these nanophthalmos complications, timely diagnosis and a suitable clinical treatment plan are vital to ensure that nanophthalmos patients are treated and managed effectively.