Evaluation of fluid leakage into the canine vitreous humor during phacoemulsification using contrast-enhanced magnetic resonance imaging

Fluid Supplementation Through Weakened Zonules via Side-Port Incision to Maintain Intraocular Pressure in High Myopic Eyes

INTRODUCTION

During phacoemulsification, the infusion pressure can cause the liquefied vitreous fluid to escape through the ciliary fiber interspace in highly myopic eyes, leading to reduced vitreous cavity pressure similar to vitrectomized eyes. This study assessed the probability of low intraocular pressure (IOP) in high myopic eyes with different axial length (AL) group undergoing cataract surgery, as well as the impact of balanced salt solution (BSS) supplementation and the optimal IOP value for such supplementation.

METHODS

The control group consisted of cataract eyes with normal AL (group 1: 22 mm ≤ AL < 24.5 mm), while cataract eyes with high axial myopia were categorized into three groups (group 2: 26 mm ≤ AL < 28 mm, group 3: 28 mm ≤ AL < 30 mm, group 4: AL ≥ 30 mm). IOP was measured using the iCare pro tonometer intraoperatively. BSS supplementation was performed to raise IOP in cases of low IOP, before intraocular lens (IOL) implantation and before the end of surgery. The probability of low IOP was calculated, and the IOP before and after supplementation were compared.

RESULTS

Ninety-five eyes were included. The total probability of low IOP in groups 2, 3, and 4 was 56.52, 62.50, and 70.83%, respectively, significantly higher than that in group 1 (16.67%). Similarly, the probability of low IOP before IOL implantation was significantly higher in groups 2, 3, 4 (43.48, 41.67, and 62.50%) compared to group 1 (4.17%, P < 0.05). The IOP before and after the first BSS supplementation in three high myopia groups were statistically significant (P < 0.05), increasing from 12.10 mmHg (range, 6.0-24.9 mmHg) to 16.60 mmHg (range, 10.2-34.4 mmHg). After the second BSS supplementation before the end of surgery, the IOP of high myopia groups increased from 12.60 mmHg (range, 7.0-25.3 mmHg) to 14.60 mmHg (range, 9.8-25.3 mmHg).

CONCLUSIONS

The condition of highly myopic eyes seems more likely to develop low IOP during cataract surgery. There is an observed correlation: as AL increases, the total probability of low IOP rises. In patients with IOP < 9.5 mmHg intraoperatively, fluid supplementation via a side-port incision can effectively raise IOP to about 16 mmHg before IOL implantation and about 14 mmHg after incision sealing, facilitating smoother IOL implantation and reducing the risk of postoperative low IOP.

TRIAL REGISTRATION

NCT, NCT05201677. Registered 23 November 2021-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05201677 .

Evaluation for endotoxin in intraocular materials used during phacoemulsification surgery using a recombinant factor C assay

OBJECTIVE

Cataract surgery remains the sole method to resolve blindness secondary to cataract formation. One complication includes fibrin web formation post-operatively. This study aimed to investigate the presence of endotoxin within materials used during cataract surgery as a possible cause of fibrin web phenomenon.

METHODS

Preservative-free epinephrine, heparin, viscoelastic devices, and intraocular lenses were collected for evaluation. Various manufacturers and manufacturing lot numbers were used when available. Viscosity of viscoelastics was reduced by incubating samples with human recombinant hyaluronidase. Intraocular product (IOL) packaging fluid was collected and stored for testing. The IOLs were then washed with a sterile balanced salt solution, incubated at 37°C for 48 h, and then fluid was collected for testing to mimic intraocular placement. Samples were tested using a commercially available rFC kit. Fluorescence was measured at time zero and after 1 h using a fluorescence microplate reader. The change in fluorescence was corrected for blank fluorescence and plotted to a standard curve.

RESULTS

Endotoxin levels were below the limit of detection (0.05 EU/mL) in all samples. Incubation of IOLs at intraocular temperature did not increase extraction of endotoxin.

CONCLUSION

Endotoxin was not identified in any tested sample, including those used in cases of fibrin web formation post-phacoemulsification. As fibrin webs are often observed episodically, it is possible that endotoxin levels may vary between batches, or that endotoxin is not related to fibrin formation.

Long-term evaluation of the effects of vitreous degeneration on cataracts and retinal detachment in dogs

OBJECTIVE

We aimed to track and evaluate the association between vitreous degeneration and the development of cataracts or retinal detachments in dogs over a long period.

ANIMAL STUDIED

Data on vitreous degeneration, cataracts, and retinal detachment in 102 eyes were collected from 68 dogs who underwent ocular ultrasonography at least twice between March 2017 and November 2021 at the Veterinary Medical Teaching Hospital, Konkuk University. The mean follow-up time was 515 ± 256 (mean ± standard deviation; range: 81-1196) days.

PROCEDURE

Development of cataracts and retinal detachment, according to the severity of vitreous degeneration grade (VDG), was evaluated during long-term follow-up.

RESULTS

In the cataract study (87 eyes, 61 dogs), the number of cataracts developed according to VDG (grade: 0-3) were as follows: VDG 0: 1 in 10 (10%) eyes, VDG 1: 15 in 35 (43%) eyes, VDG 2: 15 in 30 (50%) eyes, and VDG 3: 10 in 12 (83%) eyes. It was significantly different among grades (p = .026). In the retinal detachment study (95 eyes, 64 dogs), the number of retinal detachments developed according to each VDG were as follows: VDG 0: 0 in 11 (0%) eyes, VDG 1: 1 in 36 (3%) eyes, VDG 2: 5 in 35 (14%) eyes, and VDG 3: 4 in 13 (30%) eyes. It was also significantly different among grades (p = .019).

CONCLUSIONS

During long-term follow-up, dogs with severe vitreous degeneration had an increased risk of cataract and retinal detachment development than those without or with mild vitreous degeneration.

Prospective evaluation of the prevalence of conjunctival and intraocular bacteria in dogs undergoing phacoemulsification following a standardized aseptic preparation with 0.5% povidone iodine

PURPOSE

To evaluate bacterial contamination of conjunctiva and aqueous humor in dogs undergoing phacoemulsification following asepsis with 0.5% povidone iodine and determine the influence of intravenous antibiotics on outcome of contamination.

METHODS

Client-owned dogs were prospectively enrolled and randomly assigned to a control group, receiving 22 mg/kg intravenous cefazolin at induction prior to sampling, or experimental group receiving no antibiotic prior to sampling, masked to the surgeon. Dogs receiving antimicrobials in the pre-operative period were excluded. Asepsis was performed on all operated eyes using 0.5% iodine with minimum 3 min contact time at induction of anesthesia and repeated before surgery. A conjunctival swab and aqueous humor sample were collected prior to incision and following incision closure, respectively. Samples were submitted for aerobic and anaerobic bacterial culture and susceptibility.

RESULTS

Seventy-one eyes of 42 dogs were included. Median age was 9 years. Thirty-nine and 32/71 eyes received intravenous cefazolin and no antibiotic, respectively. Median procedure time was 40 min per eye. Conjunctival cultures were positive in 6 eyes (8.5%): Serratia marcescens (5 eyes) and Cutibacterium acnes (1 eye). Aqueous humor cultures were positive in 5 eyes (7.0%): S. marcescens (2 eyes), Pseudomonas aeruginosa (2 eyes), Staphylococcus pseudointermedius (1 eye). Prevalence of positive culture did not differ between groups (p = .74), order of eyes for bilateral procedures (p = .74) and diabetic status (p = 1).

CONCLUSIONS

Bacterial contamination of the conjunctiva and aqueous humor was present in 8.5% and 7.0% of dogs undergoing phacoemulsification after asepsis. Lack of IV cefazolin was not significantly associated with positive culture.

Comparison of Total Corneal Astigmatism between IOLMaster and Pentacam

Purpose. To compare the total corneal astigmatism (TCA) measured by IOLMaster 700 and Pentacam and to investigate the consistency of corneal keratometry (CK) measured by IOLMaster and Pentacam. Methods. Cataract patients were retrospectively enrolled in March and April, 2021. Retrospective analysis was performed on those patients with binocular and monocular CK measured by IOLMaster and Pentacam. Results. A total of 102 patients (204 eyes) were included, 64 of whom were female (62.75%). The flat (K1) and steep (K2) CK of anterior corneal surface (ACS) and flat (TK1) and steep (TK2) of total cornea measured with IOLMaster 700 were $44.16\pm 1.60\text{D}$ , $45.09\pm 1.68\text{D}$ , $44.12\pm 1.62\text{D}$ , and $45.14\pm 1.69\text{D}$ , respectively. Those measured with Pentacam were $44.31\pm 1.57\text{D}$ , $45.22\pm 1.65\text{D}$ , $44.15\pm 1.67\text{D}$ , and $45.19\pm 1.82\text{D}$ , respectively. The astigmatism of ACS and TCA were $-0.94\pm 0.63\text{D}$ and $-1.02\pm 0.69\text{D}$ ( $p<0.01$ ) in the IOLMaster group and $-0.90\pm 0.59\text{D}$ and $-1.05\pm 0.81\text{D}$ in the Pentacam group, respectively ( $p<0.01$ ). TCA measurement results of IOLMaster and Pentacam were consistent ( $\text{Pearson}=0.710$ , $p<0.01$ ), and there was no significant difference ( $p=0.591$ ). Conclusions. Total corneal astigmatism measured by IOLMaster was consistent with that measured by Pentacam. The difference between the astigmatism of anterior corneal surface and total cornea was detected in the measurement of IOLMaster and Pentacam, respectively.

Evaluation of vitreous degeneration as a potential risk factor for retinal detachment after phacoemulsification in dogs

PURPOSE

To evaluate vitreous degeneration as a potential risk factor for retinal detachment in dogs after phacoemulsification.

METHODS

Medical records for dogs with preoperative ocular ultrasound and phacoemulsification between September 28, 2006, and August 2, 2016, were reviewed. Ultrasound images were reviewed by two observers independently, and vitreous echogenicity was graded using an established scale. The following factors were compared between eyes with and without retinal detachment: signalment, operated eye, cataract stage at the time of surgery, and presence or absence of the following: lens-induced uveitis (LIU), glaucoma, anterior vitreous presentation, lens subluxation, history of prophylactic retinopexy, diabetes mellitus, operating surgeon, concurrent prophylactic retinopexy, posterior capsular tear, phacoemulsification duration, use of automated anterior vitrectomy, placement of an artificial intraocular lens, and intraocular lens type (polymethyl methacrylate or acrylic foldable). Total follow-up time was recorded. Presence and time from surgery to onset of complications were recorded. Retinal detachment was diagnosed based on observation via indirect ophthalmoscopy or ocular ultrasound.

RESULTS

Evaluation for association between vitreous degeneration and retinal detachment included 290 eyes of 180 dogs. There was no statistically significant correlation between vitreous degeneration and postoperative retinal detachment. Retinal detachment was observed in 17 of 290 eyes (5.9%). Vitreous degeneration was marked as present by at least one observer in 189 of 290 eyes (65%).

CONCLUSIONS

Ultrasonically identifiable vitreous degeneration does not correlate with increased risk of retinal detachment following phacoemulsification.

Incidence and characteristics of acute-onset postoperative bacterial and sterile endophthalmitis in dogs following elective phacoemulsification: 1,447 cases (1995-2015)

OBJECTIVE To characterize and determine the incidence of acute-onset (ie, developing ≤ 6 weeks after surgery) postoperative infectious and sterile endophthalmitis in dogs following elective cataract surgery. DESIGN Retrospective case series. ANIMALS 2,630 eyes of 1,447 dogs that underwent elective unilateral or bilateral cataract surgery by phacoemulsification at Cornell University from 1995 through 2015. PROCEDURES Medical records were reviewed to collect and summarize data regarding dog signalment, clinical findings, diagnostic test results, surgery characteristics, eye or eyes affected, concurrent major systemic diseases, treatments, and clinical outcome. RESULTS Infectious endophthalmitis developed in 4 eyes of 4 dogs during the follow-up period, representing 0.15% of eyes and 0.28% of dogs that underwent surgery. Unilateral sterile endophthalmitis developed in 3 (0.11%) eyes of 3 (0.21%) dogs. All cases of infectious endophthalmitis were unilateral and in pseudophakic eyes and followed bilateral cataract surgeries. Clinical signs consistent with infectious endophthalmitis developed a median of 18 days after surgery and included marked and progressive hypopyon; Staphylococcus or Streptococcus spp were recovered from aqueous and vitreous humor samples. All eyes with infectious endophthalmitis responded poorly to medical treatment and were enucleated. In 2 eyes with infectious endophthalmitis, corneal incision nonunion with epithelial downgrowth was identified histologically and postulated as the route of bacterial entry into the globe. CONCLUSIONS AND CLINICAL RELEVANCE Bacterial endophthalmitis following elective phacoemulsification was uncommon in the dogs of this study. Introduction of bacteria into the eye may occur during surgery or in the postoperative period from corneal incisions that fail to heal normally.

Influence of an intentionally induced posterior lens capsule rupture on the real-time intraocular pressure during phacoemulsification in canine ex vivo eyes

OBJECTIVE

To evaluate the changes in the intraocular pressure (IOP) following an intentionally induced posterior lens capsule rupture (PLCR) during phacoemulsification in enucleated canine eyes. Furthermore, to compare the IOPs between different stages of phacoemulsification for two different bottle heights (BH).

PROCEDURES

Coaxial phacoemulsification was performed using a venturi-based machine at a 60 or 90 cm BH. A pressure transducer, inserted into the anterior chamber through the peripheral cornea, monitored real-time IOP. For one half of the lens, the sculpt-segment removal (SS) was followed by irrigation/aspiration (IA). The PLCR was intentionally created, and the SS and IA were repeated on the residual lens fragments.

RESULTS

For the 60 cm BH, the mean IOP following the PLCR was significantly higher than before the PLCR during SS (28.30 ± 12.56 and 38.71 ± 9.43 mmHg before and after PLCR, respectively) and IA (42.76 ± 12.46 and 47.88 ± 7.10 mmHg before and after PLCR, respectively) stages (P < 0.001). For the 90 cm BH, the mean IOP following the PLCR was also significantly higher than before the PLCR during SS (33.39 ± 11.09 and 58.17 ± 6.89 mmHg before and after PLCR, respectively) and IA (62.39 ± 12.46 and 72.04 ± 8.59 mmHg before and after PLCR, respectively) stages (P < 0.001).

CONCLUSIONS

The occurrence of a PLCR led to an increase in IOP during both the SS and IA stages. The elevated IOP after the PLCR might be one of the most important factors for ocular tissue damage, as it reduces ocular perfusion. Additionally, the BH should be reduced following PLCR to prevent complications stemming from the raised IOP.

Real-time intraocular pressure measurement during phacoemulsification in dogs ex vivo

This study was performed to evaluate changes in intraocular pressure (IOP) during standard coaxial phacoemulsification using 4 different bottle heights (BHs) and 2 different incision sizes. Coaxial phacoemulsification was performed with a venturi-based machine in 8 enucleated canine eyes through 3.0 and 3.2 mm clear corneal incisions (CCIs). A pressure transducer inserted in the peripheral cornea monitored the IOP in real-time. The surgery was subdivided into 4 stages: sculpt-segment removal, irrigation/aspiration, capsular polishing and viscoelastic removal. The mean IOP and the difference between the maximum and minimum IOPs were calculated at each stage and compared. The ultrasound time and volume of irrigation fluid used were recorded. The mean IOP increased with an elevation in the BH. The mean IOP in the irrigation/aspiration stage was significantly higher than that in the sculpt-segment removal stage at the same BH. The difference between the maximum and minimum IOP at each stage was greater in the 3.2 mm than the 3.0 mm CCIs, although the mean IOP was lower with the 3.2 mm than the 3.0 mm CCIs. The ultrasound time and irrigation fluid volume were greater with the 3.2 mm than the 3.0 mm CCIs. Therefore, fluidic parameters during each stage could be reassessed and adjusted to reduce complications arising from an elevated IOP. Phacoemulsification with 3.0 mm CCIs at a lower BH might lead to less stress on the eye from IOP fluctuations, ultrasound energy and irrigation fluid.