Patient pain during stretching of small pupils in phacoemulsification performed using topical anesthesia

An Analysis of the Use of Proparacaine in Cataract Surgery

A cataract is the primary cause of preventable blindness and is characterized by a congenital, developmental, or acquired opacity of the human lens. Cataracts are predominantly treated through surgical procedures utilizing a combination of anesthetic agents such as proparacaine to reduce patient discomfort. Proparacaine is used to inhibit voltage-gated sodium channels on neuronal membranes to prevent signal propagation and pain signaling in the patient. Current clinical standards call for the utilization of 0.5% proparacaine when used for local anesthesia in cataract surgeries. In this review, the authors extracted the reported application site and concentrations of proparacaine in conjunction with various combination agents to accurately describe its usage in cataract surgery. It was found that most surgeons adhered to the standard concentrations of proparacaine and generally used tropicamide, an eye dilator, as a combination agent in cataract surgery. Additionally, surgeons preferred anesthetic application to the retrobulbar block. The authors find that although surgeons are following standard protocol, adjustments for lowering the standard dose of proparacaine could prove beneficial in preventing proparacaine toxicity. Furthermore, the authors find that more research can be conducted in the future examining other combination agents for use with proparacaine to improve patient outcomes.

Sox2 knockdown in the neonatal retina causes cell fate to switch from amacrine to bipolar

Transcription factor Sox2 is widely recognized for its critical roles in the nervous system, including the neural retina. Here, we aimed to reveal the function of Sox2 in the process of mouse postnatal development. After the suppression of Sox2 at P0, there was an increase number in bipolar cells but a decrease in amacrine cells. Inhibited Sox2 expression also led to decreased visual function. Furthermore, we found a distinctive type of retinal cells expressing the characteristic proteins of both bipolar cells and amacrine cells at P6, which may be an intermediate state in which amacrine cells were transforming into bipolar cells. Transcription factors associated with the development of bipolar cells and amacrine cells also support those changes. Our work indicated that inhibition of Sox2 could change cell fate by affecting transcription factors in the development of bipolar cells and amacrine cells, may provide new directions for the study and treatment of retinal genetic diseases and retinal dysplasia.

[Mechanical pupillary dilatation using rings in small pupils during cataract surgery : Video article]

OBJECTIVE

The purpose of mechanical pupillary dilatation in small pupils is a sufficient visualization of the lens to be able to perform capsulorhexis, phacoemulsification and intraocular lens implantation.

INDICATIONS

The indications for mechanical dilatation are fulfilled in patients where a sufficient pharmacological preoperative pupil dilatation is not possible.

SURGICAL TECHNIQUE

During routine cataract surgery specific foldable rings can be employed to dilate the pupil with the appropriate injector under viscoelastic substances. These rings are carefully placed at the pupillary margin until circular pupillary dilatation up to 6-7 mm is achieved. After intraocular lens implantation and before removing the viscoelastic substance the rings are slowly folded into the injector and then removed. The surgical technique is demonstrated in detail with the help of a video of the operation, which is available online.

RESULTS

Mechanical pupillary dilatation was possible in all patients studied (n = 14), which allowed uncomplicated phacoemulsification and intraocular lens implantation. For both ring systems studied the mean pupillary dilatation was 6.6 mm. At the end of surgery, the pupillary diameter was 4.89 mm using a Malyugin ring (MST, Redmond, Washington, USA) and 4.93 mm with an I‑ring (Visitec, Waltham, MA, USA; P > 0.05). Small lesions at the pupillary margin or pigment dispersion during implantation or explantation depended mostly on the individual patient situation and not on the ring used.

CONCLUSION

Mechanical pupillary dilatation with rings allows sufficient dilatation to perform cataract surgery. Both the Malyugin ring and the I‑ring achieved smooth and atraumatic pupillary dilatation.

Safety and efficacy of phacoemulsification and intraocular lens implantation through a small pupil using minimal iris manipulation

Purpose

The aim of this study was to compare the results of phacoemulsification through a small pupil using minimal iris manipulation versus phacoemulsification through a well-dilated pupil.

Methods

This prospective randomized control (comparative) study comprised 78 patients (group I) with a maximally dilated pupil size of ≤4.00 mm and 45 patients (group II) with dilated pupil size of ≥7.00 mm. In group I patients, only viscodilation and minimal push-and-pull iris stretching with two collar-button iris-retractor hooks were utilized without iris manipulation. Phacoemulsification was performed by two senior surgeons and the technique used consisted of either stop and chop or quick chop, infusion/aspiration of lens cortex, capsular bag refill with ocular viscoelastic devices, and implantation of an acrylic foldable intraocular lens. Patients were examined on the first day and 1 month postoperatively.

Results

Forty-six eyes of group I patients had pseudoexfoliation syndrome, eleven eyes had previous glaucoma surgery, 14 eyes had angle-closure or open-angle glaucoma, and seven eyes had posterior synechiae with iritis. In group I patients, the mean pupil size measured under an operating microscope was 3.2 mm preoperatively, 4.3 mm after viscoelastic and mechanical pupil dilation, and 4.1 mm at the end of a surgical procedure. Rupture of the zonular fibers occurred in six patients of group I and the intraocular lens was implanted in the sulcus. Small iris-sphincter rupture and small hemorrhages occurred in four eyes during pupillary manipulation, but they were not evident at the end of the surgery. In group II patients, no intraoperative complications occurred. Signs of significant corneal edema and iritis were observed more frequently in group I eyes (26 eyes and 20 eyes, respectively) on the first postoperative day in comparison with group II eyes (ten eyes and six eyes, respectively). Intraocular pressure was <20 mmHg in all eyes of both groups. One month postoperatively, the pupil was round and reactive to light, the anterior chamber was quiet, and the cornea was clear in all eyes. The best-corrected visual acuity on Snellen chart was 20/40 (Monoyer’s scale) or better in both groups.

Conclusion

Phacoemulsification through a small pupil using minimal iris manipulation can be safe and exhibits the same results as those obtained with phacoemulsification through normal pupils.

Comparative clinical trial of topical anaesthetic agents for cataract surgery with phacoemulsification: lidocaine 2% drops, levobupivacaine 0.75% drops, and ropivacaine 1% drops

PURPOSE

To assess the safety and efficacy of topical lidocaine, levobupivacaine, and ropivacaine in cataract surgery with phacoemulsification.

METHODS

One hundred and five patients scheduled for cataract surgery with topical anaesthesia were randomly allocated into 3 groups of 35 patients each to receive eye drops of lidocaine 2%, levobupivacaine 0.75%, or ropivacaine 1% every 5 min starting 30 min before surgery. Patients graded their pain using a 0-10-point verbal pain score (VPS) at different stages of the procedure. The levels of patient and surgeon satisfaction, the duration of surgery, complications, and the need for supplemental anaesthesia were recorded.

RESULTS

There was no significant difference in duration of surgery and demographic variables among the groups. At the intraoperative period, end of surgery, and postoperative first hour the mean VPS in the lidocaine group was significantly higher than the others (P<0.01), but no significant difference was found between the levobupivacaine and ropivacaine groups. At incision and 24 h after surgery, it was not significantly different among the groups. Surgeon and patient satisfaction scores were significantly better in the levobupivacaine and ropivacaine groups than in the lidocaine group (P<0.01).

CONCLUSIONS

Topical anaesthesia with levobupivacaine and ropivacaine were safe, feasible and more effective than lidocaine in cataract surgery. Levobupivacaine and ropivacaine provided sufficient and long-lasting analgesia without the need of supplemental anaesthesia for each patient.

SOX2 is a dose-dependent regulator of retinal neural progenitor competence

Approximately 10% of humans with anophthalmia (absent eye) or severe microphthalmia (small eye) show haploid insufficiency due to mutations in SOX2, a SOXB1-HMG box transcription factor. However, at present, the molecular or cellular mechanisms responsible for these conditions are poorly understood. Here, we directly assessed the requirement for SOX2 during eye development by generating a gene-dosage allelic series of Sox2 mutations in the mouse. The Sox2 mutant mice display a range of eye phenotypes consistent with human syndromes and the severity of these phenotypes directly relates to the levels of SOX2 expression found in progenitor cells of the neural retina. Retinal progenitor cells with conditionally ablated Sox2 lose competence to both proliferate and terminally differentiate. In contrast, in Sox2 hypomorphic/null mice, a reduction of SOX2 expression to <40% of normal causes variable microphthalmia as a result of aberrant neural progenitor differentiation. Furthermore, we provide genetic and molecular evidence that SOX2 activity, in a concentration-dependent manner, plays a key role in the regulation of the NOTCH1 signaling pathway in retinal progenitor cells. Collectively, these results show that precise regulation of SOX2 dosage is critical for temporal and spatial regulation of retinal progenitor cell differentiation and provide a cellular and molecular model for understanding how hypomorphic levels of SOX2 cause retinal defects in humans.