Wound healing of scleral self-sealing incision: a comparison of ultrasound biomicroscopy and histology findings

Comparison of VEGF level in tears post phacoemulsification between non-proliferative diabetic retinopathy and non-diabetic patients

Background

Progression of diabetic retinopathy post cataract surgery is related to the increased level of vascular endothelial growth factor (VEGF) in ocular fluid post operatively. The aim of this study was to compare the VEGF level in tears post phacoemulsification between non-proliferative diabetic retinopathy (NPDR) and non-diabetic patients.

Methods

This was a prospective cohort study and was conducted from June 2017 to May 2019. Patients with underlying NPDR who were planned for phacoemulsification were recruited in this study. Non-diabetic patients who were planned for phacoemulsification were included as control group. Tears samples were collected using Schirmer strip two weeks prior to operation, at day (D) 7 and D30 post phacoemulsification. Tears samples were analyzed for VEGF level.

Results

A total of 65 patients were recruited in this study (NPDR: 32 and control: 33). There was significant increase of VEGF levels in tears from pre operation to D7 post phacoemulsification in NPDR (p < 0.001) and control (p < 0.001). There was also significant reduction of tear VEGF level from D7 to D30 post phacoemulsification in both groups (p < 0.001 in NPDR and p = 0.027 in control). The tear VEGF level was significantly higher in NPDR group compared to control at D7 post phacoemulsification (149.4 SD 55.2 pg/mL vs 109.7 SD 48.7 pg/mL, p = 0.003).

Conclusion

VEGF level in tears showed significant elevation post early cataract surgery in NPDR compared to non-diabetic patient. Therefore, tears VEGF level may provide as a non-invasive method to predict progression of diabetic retinopathy post operation among diabetic patients.

[Refractive shift after glaucoma surgery]

Filtering glaucoma surgery can affect certain biometric features of the eye: it can change the axial length and anterior chamber depth, while redistribution of mechanical tensions in the fibrous tunic can alter the shape of the cornea. Among these changes that affect refraction, reshaping of corneal curvature is the principle one. Contrary to the expectations, and in contrast to changes associated with cataract surgery, glaucoma surgery led to decrease in vertical corneal radius (steepening) and development of the with-the-rule astigmatism. A number of studies helped reveal the features of corneal astigmatism that appears after glaucoma surgery: its power, duration, possibility of horizontal meridian flattening, influence of topical cytostatic drugs and drainage devices, etc. Potential reasons of astigmatism development were suggested: conjunctival incisions and sutures in the limbal area, quantity and strength of flap sutures, intraocular pressure level, shift of fistula edges, tissue contraction after cauterization, etc. The key role in pathogenesis of the refractive shift due to change of corneal curvature may belong to particularities of wound healing in the cornea and sclera: healing in sclera is similar to one of connective tissue - its ultrastructure undergoes aging process followed by change of rigidity. At the same time, the main reason for the development of corneal astigmatism after glaucoma surgery remains unclear.

Sustained reduction of intraocular pressure by supraciliary delivery of brimonidine-loaded poly(lactic acid) microspheres for the treatment of glaucoma

Although effective drugs that lower intraocular pressure (IOP) in the management of glaucoma exist, their efficacy is limited by poor patient adherence to the prescribed eye drop regimen. To replace the need for eye drops, in this study we tested the hypothesis that IOP can be reduced for one month after a single targeted injection using a microneedle for administration of a glaucoma medication (i.e., brimonidine) formulated for sustained release in the supraciliary space of the eye adjacent to the drug's site of action at the ciliary body. To test this hypothesis, brimonidine-loaded microspheres were formulated using poly(lactic acid) (PLA) to release brimonidine at a constant rate for 35 days and microneedles were designed to penetrate through the sclera, without penetrating into the choroid/retina, in order to target injection into the supraciliary space. A single administration of these microspheres using a hollow microneedle was performed in the eye of New Zealand White rabbits and was found to reduce IOP initially by 6 mmHg and then by progressively smaller amounts for more than one month. All administrations were well tolerated without significant adverse events, although histological examination showed a foreign-body reaction to the microspheres. This study demonstrates, for the first time, that the highly-targeted delivery of brimonidine-loaded microspheres into the supraciliary space using a microneedle is able to reduce IOP for one month as an alternative to daily eye drops.

Evaluation of mechanical closure resistance of sutureless vitrectomy sclerotomies after conjunctival cauterization with bipolar diathermy forceps

BACKGROUND

Suturing is the most widely used technique to close leaking sclerotomies after transconjunctival sutureless vitrectomy (TSV). However, with the aim of avoiding the disadvantages caused by conjunctival stitches, there have been described other closure techniques, such as the cauterization of the conjunctiva placed over the incisions. To continue advancing knowledge of the incisional occlusion effect achieved by conjunctival diathermy, it would be also interesting to study the wound closure resistance obtained under intraocular pressure (IOP) changes, given that in the early postoperative period eyes are subjected to pressure stress. In our study, we compare the mechanical resistance observed in sclerotomies treated with bipolar diathermy after TSV compared to that found in incisions in which cauterization was not performed.

METHODS

This was an experimental, randomized, and observer-masked study in which 23-gauge TSV was performed in 80 cadaveric pig eyes. Once each vitrectomy was finished, cauterization was performed with bipolar diathermy forceps on the conjunctiva placed over one of the superior sclerotomy sites; no maneuver was performed over the other superior incision. IOP was gradually increased by means of the vitrectomy system (Accurus; Alcon Laboratories, TX) until one of the superior sclerotomies opened, allowing internal ocular solution to escape.

RESULTS

In 35 % of cases (28 of 80 eyes), sclerotomies subjected to diathermy allowed intraocular fluid escape first (p = 0.01). When comparing opening pressure values, cauterized incisions leaked at significantly higher pressure levels than those in which diathermy was not applied (p < 0.001).

CONCLUSIONS

Bipolar diathermy on sutureless sclerotomies has demonstrated to be, in our experimental model, an effective method for increasing the sclerotomy closure resistance. Although its use in vitrectomized eyes has previously been described, our study is the first to analyze the response of cauterized sclerotomies to IOP increases.

Assessment of Closure Competency of Sutureless Vitrectomy Sclerotomies After Scleral Hydration

PURPOSE

To assess the influence that hydration applied on the sclerotomy edges may have on incisional closure resistance after transconjunctival sutureless vitrectomy (TSV).

METHODS

Experimental, randomized and observer-masked study in which 23-gauge TSV was performed in 80 cadaveric pig eyes. Once each vitrectomy was finished, hydration with balanced salt solution (BSS) was applied on the sclerotomy edges of one of the superior incision sites; no maneuver was performed on the other superior sclerotomy. Intraocular pressure (IOP) was gradually increased by means of the vitrectomy system (Accurus; Alcon Laboratories, TX) until one of the superior sclerotomies opened, allowing internal ocular solution to escape.

RESULTS

In 45% of cases (36 of 80 eyes), sclerotomies subjected to hydration allowed intraocular fluid escape (p = 0.43). There were no differences when comparing opening pressure values of hydrated and non-hydrated sclerotomies (p = 0.19).

CONCLUSIONS

Scleral hydration did not demonstrate increase in the sclerotomy closure resistance in our experimental model. Given the widespread use of sutureless TSV around the world, the results obtained in our research, in spite of being negative, may contribute to the knowledge of the behavior of sutureless sclerotomies.

Anatomic and pharmacokinetic properties of intravitreal bevacizumab and ranibizumab after vitrectomy and lensectomy

PURPOSE

To determine the anatomic characteristics and pharmacokinetic properties of intravitreally placed bevacizumab and ranibizumab after pars plana lensectomy or pars plana vitrectomy and to compare these with nonoperated control eyes in a rabbit model.

METHODS

Three groups of six Dutch-belted rabbits each underwent pars plana vitrectomy, pars plana lensectomy, or served as nonsurgical controls. Twelve days after surgery, 3 rabbits from each group underwent intravitreal injection in one eye with 1.25 mg/0.05 mL I-124-bevacizumab or 0.5 mg/0.05 mL I-124-ranibizumab. Serial imaging with integrated positron emission and computed tomography (PET/CT) were obtained on Days 0, 2, 5, 7, 14, 21, 28, and 35. Measured radioactivity emission in becquerels/milliliter was used to calculate the half-lives for each agent.

RESULTS

The intravitreally placed radiolabeled agents were contained within the vitreous cavity for the duration of the study. The average clearance half-lives with standard error for bevacizumab and ranibizumab after correction for radioactive decay were, respectively, 4.22 ± 0.07 days and 2.81 ± 0.05 days in unoperated eyes, 2.30 ± 0.09 days (P < 0.0001) and 2.13 ± 0.05 days (P < 0.0001) after vitrectomy, and 2.08 ± 0.07 days (P = 0.0001) and 1.79 ± 0.05 days (P < 0.0001) after lensectomy.

CONCLUSION

Intravitreal retention was longer for bevacizumab than ranibizumab within all study groups and was significantly reduced after vitrectomy and lensectomy for both agents. Consideration for more frequent intravitreal anti-vascular endothelial growth factor dosing regimens may be made for patients whose treated eyes have undergone previous vitrectomy or who are aphakic.

Evaluation of conjunctival bleb detection after vitrectomy by ultrasound biomicroscopy, optical coherence tomography and direct visualization

PURPOSE

To compare ultrasound biomicroscopy (UBM), anterior-segment optical coherence tomography (AS-OCT), and direct visualization for detecting conjunctival blebs in sutureless sclerotomies after vitrectomy. Conjunctival blebs are formed by sclerotomy leakage due to incompetent closure.

METHODS

Experimental, randomized, and observer-masked study in which 23-gauge vitrectomies were performed in cadaveric pig eyes. Postoperative conjunctival blebs were assessed by UBM, AS-OCT, and direct visualization. No conjunctival blebs were classified as Grade 0 (G0), thin blebs (less than or equal to one-half of scleral thickness) as Grade 1 (G1) and thick blebs (greater than one-half of scleral thickness) as Grade 2 (G2).

RESULTS

Fifty pig eyes were included. Conjunctival blebs were found in 13.3% (8% G1, 5.3% G2) of the incisions analyzed by UBM, in 20% (14.7% G1, 5.3% G2) of the sclerotomies studied by AS-OCT, and in 7.3% (2% G1, 5.3% G2) of the wounds evaluated by direct visualization. AS-OCT was the most sensitive method for identifying conjunctival blebs when compared with UBM and direct visualization (p<0.001). In turn, UBM was better than direct visualization for observing sclerotomy blebs (p=0.004).

CONCLUSIONS

AS-OCT is the most sensitive technique for detecting subclinical blebs (G1) and thus, it may be useful in research for studying the influence that surgical factors and maneuvers may exert on sclerotomy closure capacity after vitrectomy. Direct visualization, that is used in routine clinical practice to determine which sclerotomies should be sutured, is useful only to identify thick blebs (G2) after vitrectomy.

Ultrasound biomicroscopy study of direct and oblique 25-gauge vitrectomy sclerotomies

PURPOSE

To study 25-gauge sclerotomy healing process in vivo with ultrasound biomicroscopy (UBM) in direct and oblique incisions.

DESIGN

Prospective interventional case series report.

METHODS

At our institution, we performed UBM studies on 53 sclerotomies during the first 30 days after 25-gauge vitrectomy, looking for conjunctival bleb development, sclerotomy healing signs, and vitreous incarceration in the wound.

RESULTS

Echographical healing signs were completed in 77% of patients by day 15 with no differences between direct and oblique sclerotomies. By day 30, all but one sclerotomy were closed. Conjunctival blebs developed over 64% of direct sclerotomies, and 25% of oblique (P = .0059), but all resolved spontaneously by day 15. Vitreous incarceration appeared in 72% of sclerotomies.

CONCLUSIONS

Twenty-five gauge sclerotomies heal by day 15 in most cases with no difference between direct and oblique sclerotomy construction. Conjunctival blebs developed more frequently over direct than oblique sclerotomies.