Comparative histopathology of cryosurgery and photocoagulation. Observations on the advantages of cryosurgery in retinal detachment operations

Cooling Anesthesia for Intravitreal Injection: Results of the Prospective Open-Label, Dose-Ranging COOL-1 Trial

Purpose

To evaluate the safety and efficacy of a novel medical device to provide cooling anesthesia to the eye as local anesthesia for intravitreal injections.

Study Design

First in human, open-label study of 43 subjects assessed at three different doses: −10°C for 20 seconds (group 1), −15°C for 15 seconds (group 2), and −15°C for 20 seconds (group 3). Main outcome measures were safety and pain of injection using a numeric rating scale (NRS).

Results

Cooling anesthesia did not result in any serious ocular adverse events. One grade 1 adverse event was a vasovagal response during cooling administration which resolved immediately after cooling. Mean NRS scores at the time of injection for each group ranged from 2.5 to 4.3 There was a statistically significant difference between pain scores of the 3 groups at injection in aggregate but not in pairwise comparisons (P value = 0.047). There was a statistically significant decrease in pain from injection to 5 minutes post injection in all groups (P value = 0.00008, 0.003, 0.0005 for groups 1, 2, 3, respectively) as well as from 5 minutes to 24–48 hours (P value = 0.00001, 0.018, and 0.0545 for groups 1, 2, 3, respectively).

Conclusion

The rapid cooling anesthesia device was well tolerated for achieving local anesthesia among patients receiving intravitreal injections with no serious ocular adverse events.

Randomized Safety and Feasibility Trial of Ultra-Rapid Cooling Anesthesia for Intravitreal Injections

PURPOSE

To test the safety and preliminary efficacy of rapid, nonpharmacologic anesthesia via cooling for intravitreal injections.

DESIGN

Single-center, randomized phase 1 dose-ranging safety study (ClinicalTrials.gov identifier, NCT02872012).

PARTICIPANTS

Adults 18 years of age or older with a diagnosis of exudative macular degeneration or diabetic macular edema requiring bilateral anti-vascular endothelial growth factor therapy were included.

METHODS

A handheld device was developed to provide anesthesia via cooling to a focal area on the surface of the eye before intravitreal treatment (IVT). In 22 patients undergoing bilateral IVT, 1 eye was randomized to receive standard of care (SOC) lidocaine-based anesthesia and the other eye received cooling-anesthesia at 1 of 5 different temperatures and cooling times. Subjective pain was assessed via the visual analog scale (VAS; range, 1-10) at 2 time points: (1) immediately after IVT and (2) 4 hours after IVT. Treated eyes were assessed for ocular safety 24 hours after IVT.

MAIN OUTCOME MEASURES

We determined the occurrence of adverse events in eyes treated with cooling anesthesia. Mean VAS pain scores immediately after IVT and 4 hours after IVT in eyes receiving cooling anesthesia were compared with eyes receiving SOC.

RESULTS

A total of 44 eyes were treated, 22 with cooling anesthesia and 22 with SOC. No dose-related toxicity was found with cooling anesthesia. Mild, transient adverse events were recorded in 32% of patients treated with cooling anesthesia versus 44% of patients receiving SOC. The mean±standard error of the mean (SEM) VAS pain scores immediately after intravitreal injection were 2.3 ± 0.4 for patients receiving SOC and 2.2 ± 0.6 in patients receiving -10° C cooling anesthesia (P = 0.8). Mean±SEM pain scores 4 hours after injection were 1.6 ± 0.4 for SOC and 1.2 ± 0.5 in the combined -10° C arms (P = 0.56). Total mean±SEM procedure time was 124 ± 5 seconds for patients treated with cooling anesthesia versus 395 ± 40 seconds for SOC (P < 0.0001).

CONCLUSIONS

Ultra-rapid cooling of the eye for anesthesia was well tolerated, with -10° C treatment resulting in comparable levels of anesthesia to SOC with a reduction in procedure time.

Anterior retinal cryotherapy and intravitreal injection of bevacizumab in the treatment of nonclearing vitreous hemorrhage in proliferative diabetic retinopathy

PURPOSE

To evaluate the efficacy of intravitreal bevacizumab (IVB) injection combined with anterior retinal cryotherapy (ARC) in the treatment of proliferate diabetic retinopathy (PDR) with vitreous hemorrhage (VH).

METHODS

A retrospective case controlled study was performed on 67 cases (67 patients) with PDR and persistent VH obscuring the fundus detail for ≧3 weeks. The follow-up period was ≧6 months. Cases with extensive vitreo-retinal adhesion by ultrasonography were excluded. In the study group, transconjunctival ARC (a total of 12 spots) followed by IVB 1.25 mg was performed in the same setting; in the control group, only IVB was given. Panretinal photocoagulation was performed when possible. Repeated IVB was performed in both groups if VH persisted for >4 weeks following the initial treatment. Vitrectomy was performed if VH showed no improvement for 12 to 16 weeks. The vitreous clear-up time (VCUT) in the posterior pole and the rate of vitrectomy were compared between the 2 groups.

RESULTS

In the study group (n=35), second treatment was required in 7 out of 35 patients (20.0%). Vitrectomy was performed in 5 (14.3%) patients. In the control group (n=32), 8 out of 32 eyes (25.0%) underwent second injection. Four eyes (12.5%) had vitrectomy within the follow-up time. VCUT in the study and the control group was 6.9±8.7 weeks and 13.0±9.3 weeks respectively (P=0.003).

CONCLUSION

Combined treatment of ARC and IVB is associated with more rapid clearing of VH in eyes with PDR compared with IVB alone.

Pathophysiology of proliferative vitreoretinopathy in retinal detachment

Because proliferative vitreoretinopathy cannot be effectively treated, its prevention is indispensable for the success of surgery for retinal detachment. The elaboration of preventive and therapeutic strategies depends upon the identification of patients who are genetically predisposed to develop the disease, as well as upon an understanding of the biological process involved and the role of local factors, such as the status of the uveovascular barrier. Detachment of the retina or vitreous activates glia to release cytokines and ATP, which not only protect the neuroretina but also promote inflammation, retinal ischemia, cell proliferation, and tissue remodeling. The vitreal microenvironment favors cellular de-differentiation and proliferation of cells with nonspecific nutritional requirements. This may render a pharmacological inhibition of their growth difficult without causing damage to the pharmacologically vulnerable neuroretina. Moreover, reattachment of the retina relies upon the local induction of a controlled wound-healing response involving macrophages and proliferating glia. Hence, the functional outcome of proliferative vitreoretinopathy will be determined by the equilibrium established between protective and destructive repair mechanisms, which will be influenced by the location and the degree of damage to the photoreceptor cells that is induced by peri-retinal gliosis.

Multifocal electroretinography amplitudes increase after photocoagulation in areas with increased retinal thickness and hard exudates

PURPOSE

This study aimed to evaluate local response on multifocal electroretinography (mfERG) and to assess retinal thickness with optical coherence tomography (OCT) after focal laser treatment in areas with retinal oedema and exudates in patients with diabetic retinopathy.

METHODS

Twelve diabetes patients (aged 60 +/- 14 years, diabetes duration 16 +/- 8 years) treated with focal or grid photocoagulation in areas with retinal oedema and/or exudates underwent mfERG and OCT before and 3 months after treatment. The average thickness (in microm) in any of the nine sectors (defined according to the ETDRS) treated with photocoagulation was measured. Amplitudes and implicit times were analysed in corresponding areas on the mfERG.

RESULTS

Mean mfERG amplitudes increased after photocoagulation (21.5 +/- 8.0 nV/deg(2) versus 16.8 +/- 6.1 nV/deg(2); p = 0.012), whereas no difference was seen in implicit times. Mean OCT values in the treated regions were lower at follow-up (272 +/- 23 microm versus 327 +/- 79 microm; p = 0.013). No correlation was seen between changes in mfERG response and changes in OCT values. The decrease in retinal thickness was correlated with the number of laser spots applied (p = 0.002).

CONCLUSIONS

Focal argon laser treatment is effective in reducing retinal thickness. In addition, treated areas tend to show improved retinal function as demonstrated by increased amplitudes on mfERG.

Intrusion of an encircling buckle after retinal detachment surgery

PURPOSE

To report a patient with intrusion of the encircling buckle late postoperatively after surgical treatment of a rhegmatogenous retinal detachment.

DESIGN

Interventional case report.

METHODS

We performed an encircling buckle procedure on a 77-year- old woman with a rhegmatogenous retinal detachment. Four years after the operation, the encircling buckle intruded into the vitreous cavity.

RESULTS

After 3 months of diagnosis of the intrusion, the retina was detached totally.

CONCLUSIONS

Intrusion of the encircling buckle without any additional segmental buckling element is a very rare late complication of retinal detachment surgery.

Pathology and pathogenesis of retinal detachment

Retinal detachment, separation of the neurosensory retina from the underlying retinal pigment epithelium, is a sight threatening condition that is considered one of the few ocular emergencies. The literature is enormously rich in studies that focused on different aspects of this disease process. Yet certain aspects remain largely unanswered. We briefly review major aspects of retinal detachment and discuss various important contributions in this field, focussing mainly on the pathogenesis of and predisposing factors to retinal detachment, and on the pathologic changes that occur following its development and following various surgical procedures currently used in its management.

Scleral buckling technique without retinopexy for treatment of rhegmatogeneous: a pilot study

PURPOSE

To evaluate the role of retinopexy in the surgical management of primary rhegmatogenous retinal detachment (RD) without proliferative vitreoretinopathy. The primary outcome was retinal attachment, and secondary outcomes were visual acuity results and complications.

METHODS

A randomized controlled trial including 60 patients with RD caused by a break or a group of breaks no larger than one clock hour. Thirty eyes received no retinopexy (group 1), and 30 eyes received transscleral cryotherapy (group 2). An encircling buckle was placed in all eyes. In eyes with posterior breaks, segmental buckles were also added. In some eyes, subretinal fluid drainage or anterior chamber paracentesis and/or intravitreal air bubble injection was performed.

RESULTS

No differences were found between the groups in terms of the preoperative clinical variables evaluated: age; sex; axial length; lens status; type, number, and location of breaks; extension of detachment; and macula status. There were no differences in the surgical procedures performed. The reattachment rate in group 1 was 90%, and in group 2, it was 87% (a difference that was not significant [P = 1.00]). Final visual acuity improved by two lines or more in 22 patients in group 1 and in 20 patients in group 2 (P = 0.317).

CONCLUSIONS

Our results indicate that primary rhegmatogenous RD can be successfully treated with scleral buckling without retinopexy.

Erosion and intrusion of silicone rubber scleral buckle. Presentation and management

OBJECTIVE

To describe the clinical presentation and management of erosion and intrusion of silicone rubber implants that are used in scleral buckling procedures for the treatment of retinal detachment.

METHODS

The authors identified four patients from their practices during the last 20 years (1978-1998) who had erosion or intrusion of silicone rubber scleral buckles that were used to manage retinal detachment. Approximately 4400 scleral buckling procedures were performed during this period. A retrospective review of the medical records of all patients was performed. Factors that influenced management decisions concerning the intruding buckle are emphasized.

RESULTS

All four patients had myopia. The interval between placement of the scleral buckle and development of intrusion ranged from 1 to 20 years. The buckles were intrascleral in three cases and episcleral in one. Recurrent detachment and vitreous hemorrhage were indications for surgical intervention in three cases. After the surgical removal of buckling elements, visual acuity stabilized in all patients and the retina remained attached in all cases.

CONCLUSIONS

Erosion and intrusion of scleral buckle are rare complications of scleral buckling procedures. The intruding buckle may be left intact unless there is significant threat to the integrity of ocular structures, recurrent detachment, or hemorrhage. Manipulation of the encircling band or buckle does not necessarily alter the visual acuity or the status of the retina.

Retinal lesions experimentally produced by intravitreal ultrasound

Currently, vitreous surgical techniques combined with phakoemulsification are an established procedure for the removal of luxated natural lenses or dislocated lenticular material. This has proven to be a safe procedure, but occasionally retinal lesions have been inadvertently created. We describe the ophthalmoscopic and morphologic features of ultrasonically induced retinal lesions in rabbit eyes using a similar technique. The retina was treated directly using a conventional ultrasound tip for pars plana lensectomy (Fragmatome). Ophthalmoscopically slight lesions corresponded to an area of retinal whitening. More severe lesions showed a destruction of the inner retina and created a retinal break. Extensive effects also involved the choroid and led to a retinal defect with rupture of choroidal vessels and heavy bleeding into the vitreous cavity. Histologic evaluation showed that the acoustic energy primarily led to damage of the outer retina, later involving the inner retina and the choroid as well.

Rapid enhancement of retinal adhesion by laser photocoagulation

To determine how quickly laser photocoagulation produces a bond between retina and pigment epithelium, the authors measured the strength of retinal adhesion after making laser burns through intact and recently reattached rabbit retina. After photocoagulation of intact retina, the adhesive force was reduced 50% at 8 hours but increased beyond normal (to approximately 140%) by 24 hours and remained twice normal between 3 days and 4 weeks. Photocoagulation of retina that had just settled after experimental detachment produced similar results, except that the maximum strength of adhesion (reached at 2 weeks) was three times normal. In contrast, retina that reattached spontaneously, without photocoagulation, showed only 10% of normal adhesiveness at 24 hours, and still was only 75% of normal after 4 weeks. These data suggest that laser photocoagulation may be acutely beneficial in the prevention or management of retinal tears and detachments.

Peripheral retinal cryopexy for subtotal vitreous hemorrhage

We used peripheral retinal cryopexy to treat 20 eyes in 15 patients with subtotal vitreous hemorrhage secondary to proliferative diabetic retinopathy. In 18 eyes, complete panretinal photocoagulation had been performed before the subtotal vitreous hemorrhage and the subsequent cryopexy. The length of follow-up averaged 16 months. The vitreous hemorrhage completely cleared in 11 eyes (55%) and partially cleared in six eyes (30%). Visual acuity after treatment improved in 13 eyes (65%), remained unchanged in six eyes (30%), and decreased in one eye (5%).

Inflammation and the formation of epiretinal membranes

In this review of the literature evidence is provided from clinical, histological and experimental sources that inflammatory processes play a central role in the pathogenesis of contractile epiretinal membranes and proliferative vitreoretinopathy.

Dexamethasone and indomethacin attenuate cryopexy. Induced breakdown of the blood-retinal barrier

Pigmented rabbits were pretreated for 3 days with dexamethasone (0.4 mg/kg) or indomethacin (6 mg/kg tid) and then, along with control rabbits, treated with cryopexy administered to the peripheral retina. Drug treatment was continued for the duration of the study. Vitreous fluorophotometry (VFP) was performed prior to cryopexy and on postcryopexy days 3 and 7. Breakdown of the blood-retinal barrier occurred in all three groups but was significantly greater in the control group. Differences were most marked on postcryopexy day 7 when intravitreous fluorescein leakage was decreased to 36% of control in dexamethasone-treated rabbits and 42% of the control group in indomethacin-treated rabbits. Some rabbits, after dexamethasone or indomethacin treatment for 3 days, were given a single posterior cryoapplication just inferior to the optic nerve. On postcryopexy days 1, 3, 7, and 10, VFP was performed by scanning over the treated area. In control rabbits, fluorescein leakage increased over 3 days, while in dexamethasone- and indomethacin-treated rabbits, this increase was significantly blunted. These data demonstrate the beneficial effects of dexamethasone and indomethacin on cryopexy-induced breakdown of the blood-retinal barrier and also suggest a possible mechanism for how such a breakdown occurs.

Histopathologic study of the effect of retinal detachment surgery on 49 eyes obtained post mortem

We studied 49 eyes obtained post mortem from 43 patients who had previously had retinal detachment surgery to evaluate some of the factors known to complicate retinal detachment. The retina had been successfully reattached in 44 of 49 eyes. We found epiretinal membranes in 37 eyes (75.5%), and in 15 eyes (30.6%) these membranes caused some degree of macular pucker. Other important findings included atrophy of the photoreceptor layer in 13 eyes (26.5%), intrusion of the implant in ten eyes (21.7%), cystoid macular edema in five eyes (10.2%), ciliochoroidal effusion in five eyes (10.2%), anterior segment necrosis in four eyes (8.2%), and choroidal neovascularization in three eyes (6.1%).

[Focal epiretinal fibroplasias overlying photocoagulations in diabetic retinopathy (author's transl)]

This clinico-pathological study compares photocoagulated diabetic retinae with cases of spontaneous epiretinal fibroplasia. Focal epiretinal fibroplasias were found overlying 5-10% of the Xenon-arc photocoagulations but not over Ruby-laser coagulations. These foci are contiguous-forming membranes but they do not cause surface wrinkling. The topography and appearance of the fibrous components of these membranes in trypsin-digest specimens are described and compared with foci of spontaneous epiretinal surface wrinkling. Destruction of the inner retinal surface by heavy coagulation is believed to be the principal cause of focal post-photocoagulation fibroplasia. Other possible pathogenetic factors are discussed.

[Retinal adhesion after retinal detachment surgery (author's transl)]

The effect of cryotherapy was studied in experimentally detached retinas under conditions similar to those in retinal detachment surgery. When cryotherapy was applied to the pigment epithelium and to the retina and the retina was reattached, a strong adhesion developed, characterized by the occurrence of true cell junctions between pigment epithelium and retinal cells. When only the pigment epithelium was treated, the adhesion after reattachment appeared weak due to the absence of microvillous interdigitations normally present between pigment epithelium and retina.

Electron microscopy study of cryogenic chorioretinal adhesions

By electron microscopy, the cryogenic chorioretinal adhesions in eight-day-old lesions from human eyes lacked anatomic adhesion between retina and choroid. In eight-month-old lesions, the neurosensory retina adhered to the retinal pigemtn epithelial layer by both desmosomal attachments and villous interdigitation.

Tensile strength of chorioretinal lesions produced by photocoagulation, diathermy, and cryopexy

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