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Romano MR, Barachetti L, Ferrara M, Mauro A, Crepaldi L, Bronzo V, Franzo G, Ravasio G, Giudice C. Temperature control during pars plana vitrectomy. Graefes Arch Clin Exp Ophthalmol 2024:10.1007/s00417-024-06631-6. [PMID: 39249514 DOI: 10.1007/s00417-024-06631-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 08/23/2024] [Accepted: 08/29/2024] [Indexed: 09/10/2024] Open
Abstract
PURPOSE To evaluate the impact of temperature-controlled pars plana vitrectomy (PPV) on structural and functional outcomes in a rabbit eye model in vivo. METHODS Ten healthy New Zealand White rabbits underwent temperature-controlled PPV in the right eye (group A), using a device specifically designed to heat the infusion fluid/air and integrated into the vitrectomy machine, and conventional PPV in the left eye (group B). Both eyes received ophthalmic examination and electroretinography (ERG) before and 1 week postoperatively. After 1-week ERG, rabbits were enucleated and then sacrificed. Histological and immunohistochemical examinations were performed on enucleated eyes and expression of glial fibrillary acidic protein (GFAP) and vimentin investigated. RESULTS Postoperatively, only group B showed significantly decreased amplitude and increased latency of a-wave at 3 cd·s/m2 (p = 0.001 and 0.005, respectively). Significant increase of b-wave latency at 0.01 cd·s/m2 was detected in both groups (p = 0.019 and 0.023, respectively). Postoperatively, amplitude of oscillatory potentials (OPs) increased significantly in group A (p = 0.023) and decreased in group B. In both groups, OPs latency significantly increased at 1-week test (P < 0.05). A greater number of eyes without structural retinal alterations was detected in group A compared to group B (6 vs 5, respectively). GFAP expression was higher in group B than group A, even if the difference was not statistically significant. CONCLUSION Temperature-controlled PPV resulted in more favorable functional and structural outcomes in rabbit eyes compared with conventional PPV, supporting the potential beneficial role of the intraoperative management of intraocular temperature in vitreoretinal surgery.
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Affiliation(s)
- Mario R Romano
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Moltalcini 4, 20072, Pieve Emanuele-Milano, Italy.
- Department of Ophthalmology, Humanitas Gavazzeni-Castelli, Bergamo, Italy.
| | - Laura Barachetti
- Polo Oculistico Veterinario, Milan, Italy
- Department of Veterinary Medicine and Animal Sciences (DIVAS), University of Milan, Lodi, Italy
| | - Mariantonia Ferrara
- Eye Unit, ASST Spedali Civili Di Brescia, Brescia, Italy
- Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, University of Brescia, Brescia, Italy
- School of Medicine, University of Malaga, Malaga, Spain
| | - Alessandro Mauro
- Department of Engineering, University of Naples "Parthenope", Naples, Italy
| | - Lorenzo Crepaldi
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Moltalcini 4, 20072, Pieve Emanuele-Milano, Italy
| | - Valerio Bronzo
- Department of Veterinary Medicine and Animal Sciences (DIVAS), University of Milan, Lodi, Italy
| | - Giovanni Franzo
- Department of Animal Medicine, Production and Health, Padua University, Padua, Italy
| | - Giuliano Ravasio
- Department of Veterinary Medicine and Animal Sciences (DIVAS), University of Milan, Lodi, Italy
| | - Chiara Giudice
- Department of Veterinary Medicine and Animal Sciences (DIVAS), University of Milan, Lodi, Italy
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Anatychuk L, Zadorozhnyy O, Naumenko V, Maltsev E, Kobylianskyi R, Nazaretyan R, Umanets M, Kustryn T, Nasinnyk I, Korol A, Pasyechnikova N. Vitreoretinal Surgery with Temperature Management: A Preliminary Study in Rabbits. Ther Hypothermia Temp Manag 2023; 13:126-133. [PMID: 36827431 DOI: 10.1089/ther.2022.0044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
Abstract
The present study aimed to evaluate the structure of the rabbit retina after vitreoretinal surgery using prolonged irrigation with solutions of different temperatures. Thirty-six rabbits (72 eyes) were included in this study and randomly divided into 3 equal groups according to the temperature of the intraocular irrigating fluid they received during vitrectomy. Vitreoretinal surgery was performed with a 5°C irrigation solution in group 1 (12 rabbits, 24 eyes), a 22°C irrigation solution in group 2 (12 rabbits, 24 eyes), and a 36°C irrigation solution in group 3 (12 rabbits, 24 eyes). In each group of animals, the mean irrigation/aspiration time was 30 minutes for left eyes and 60 minutes for right eyes. Histological examination of the retina was performed 1, 7, and 30 days after surgery. During surgery, the temperature in the vitreous cavity of the eyes of rabbits of groups 1, 2, and 3 dropped by 26.0°C, 11.2°C (deep hypothermia), and 1.0°C (mild hypothermia), respectively. The highest rewarming rate was detected in group 1 (0.9°C/min) compared with group 2 (0.7°C/min) and group 3 (0.2°C/min). After 60 minutes of irrigation, retinal structural changes were detected in the animals of groups 1 and 2 (in contrast to the animals of group 3). After surgery with irrigation lasting 30 minutes, no retinal structural changes were observed. This study showed that temperature management, avoidance of intraoperative deep hypothermia, and prevention of rapid uncontrolled rewarming may protect the retinal morphology and increase the safety of prolonged vitreoretinal surgery.
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Affiliation(s)
- Lukyan Anatychuk
- Medical Department, Institute of Thermoelectricity of the National Academy of Sciences of Ukraine and the Ministry of Education and Science of Ukraine, Chernivtsi, Ukraine
- Department of Thermoelectricity, Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine
| | - Oleg Zadorozhnyy
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Volodymyr Naumenko
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Eduard Maltsev
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Roman Kobylianskyi
- Medical Department, Institute of Thermoelectricity of the National Academy of Sciences of Ukraine and the Ministry of Education and Science of Ukraine, Chernivtsi, Ukraine
- Department of Thermoelectricity, Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine
| | - Rudolph Nazaretyan
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Mykola Umanets
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Taras Kustryn
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Illia Nasinnyk
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Andrii Korol
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
| | - Nataliya Pasyechnikova
- Department of Laser Microsurgery of Eye Diseases, State Institution "The Filatov Institute of Eye Diseases and Tissue Therapy of the National Academy of Medical Sciences of Ukraine," Odesa, Ukraine
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Yıldız SÇ, Seyyar SA, Saygılı O, Kimyon S, Mete A, Güngör K. Effect of Irrigation Solution Temperature on the Corneal Endothelial Functions in Posterior Vitrectomy: Room Temperature Versus Cooled. Eye Contact Lens 2023; 49:296-300. [PMID: 37171496 DOI: 10.1097/icl.0000000000000998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2023] [Indexed: 05/13/2023]
Abstract
PURPOSE To compare the effects of cooled and room temperature irrigation on the preoperative and early postoperative corneal endothelial parameter values in posterior vitrectomy. MATERIALS AND METHODS In this prospective, randomized, comparative study, 68 patients underwent a standard 3-port, 23-G posterior vitrectomy operation by a single surgeon. Cooled irrigation solution was applied to 36 patients during surgery (group 1), and room temperature irrigation solution was applied to 32 patients (group 2). The patients were also divided into four groups according to their history of noncomplicated cataract surgery (phakic or pseudophakic) and the types of tamponade used (silicone or gas). The central corneal thickness (CCT), endothelial cell density (ECD), mean cell area (MCA), hexagonal cell percent, and coefficient of variation of cell area (CV) parameter values of the groups at preoperative and postoperative 1 month were compared. RESULTS There were no statistically significant differences between the preoperative and postoperative corneal parameter values in groups 1 and 2 ( P >0.05). However, it was remarkable that the percentage of preoperative-postoperative change in all the corneal parameter values was higher in group 2. When the results of the subgroup analyses of the patients who were pseudophakic and used gas tamponade (Group D) in group 2 were examined, it was determined that the negative effects were significantly higher in the postoperative values for the ECD, MCA, CV, and CCT parameters compared with the preoperative values ( P <0.05). CONCLUSION In patients with pseudophakia and gas tamponade, cooled irrigation was found to be more advantageous for corneal parameters.
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Affiliation(s)
- Seda Çeri Yıldız
- Ophthalmology Department (S.Ç.Y.), Gaziantep Abdulkadir Yuksel State Hospital, Gaziantep, Turkey; and Ophthalmology Department (S.A.S., O.S., S.K., A.M., K.G.), Gaziantep University Hospital, Gaziantep, Turkey
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Research Progress of the Application of Hypothermia in the Eye. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:3897168. [PMID: 33381263 PMCID: PMC7758138 DOI: 10.1155/2020/3897168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023]
Abstract
Hypothermia is widely used in the medical field to protect organs or tissues from damage. Different research fields have different explanations of the protection mechanism of hypothermia. Hypothermia is also widely used in the field of ophthalmology, for example, in the eye bank, the preservation of corneal tissue and the preservation of the eyeball. Low temperature can also be applied to some ophthalmic diseases, such as allergic conjunctivitis, retinal ischemia, and retinal hypoxia. It is used to relieve eye symptoms or reduce tissue damage. Hypothermic techniques have important applications in ophthalmic surgery, such as corneal refractive surgery, vitrectomy surgery, and ciliary body cryotherapy for end-stage glaucoma. Hypothermia can reduce the inflammation of the cornea and protect the retinal tissue. The eyeball is a complex organ, including collagen tissue of the eyeball wall and retinal nerve tissue and retinal blood vessels. The mechanism of low temperature protecting eye tissue is complicated. It is important to understand the mechanism of hypothermia and its applications in ophthalmology. This review introduces the mechanism of hypothermia and its application in the eye banks, eye diseases (allergic conjunctivitis, retinal ischemia, and hypoxia), and eye surgeries (corneal transplant surgery, corneal refractive surgery, and vitrectomy).
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Zhang S, Wang J, Liu J. Cryoirrigation in phacoemulsification facilitates a quicker cornea endothelia recovery. Can J Ophthalmol 2009; 44:446-50. [PMID: 19606169 DOI: 10.3129/i09-116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
OBJECTIVE To compare the recovery of cornea endothelia after phacoemulsification (phaco) with anterior chamber irrigation at different temperatures. STUDY DESIGN A between-group design was used. PARTICIPANTS Thirty-eight patients with cataract. METHODS Phaco was done on 40 eyes in these patients with exactly the same procedure except for the temperature of the anterior chamber: cryoirrigation at 12 masculine C for group 1 and at room temperature (25 masculine C) for group 2, 20 eyes in each group, randomly distributed. The cornea edema, keratic precipitate (KP), and anterior chamber flare were observed with micro-slit lamp and graded on a 4-point scale at 1, 3, and 7 days after surgery and compared between groups. RESULTS The corneas in group 1 were found to be clearer than those in group 2 at 1 and 3 days after surgery. The difference was statistically significant (p < 0.05) in favour of group 1, suggesting a lighter reaction of cornea endothelia and a quicker recovery in group 1 after the surgery with cryoirrigation. Corresponding recovery in group 2 was found to occur latterly between day 3 and day 7. However, the recovery in both groups was complete, yielding no difference between groups, at day 7 after surgery. In addition, no significant difference was found in Tyndall phenomenon and KP between groups. CONCLUSIONS Cryoirrigation during phaco could reduce postoperative cornea edema and promote recovery. The result advocates the use of cryoirrigation in clinic.
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Affiliation(s)
- Shu Zhang
- Department of Ophthalmology, Second Affiliated Hospital of Nanjing Medical University, Xia Guan, Jiang Jia Yuan No. 121, Nanjing, China.
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Kataoka T, Zako M, Takeyama M, Ohno-Jinno A, Sugenoya J, Iwaki M. Cooling Prevents Induction of Corneal Damage by Argon Laser Peripheral Iridotomy. Jpn J Ophthalmol 2007; 51:317-324. [DOI: 10.1007/s10384-007-0460-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 05/21/2007] [Indexed: 11/28/2022]
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Kunikata H, Tomita H, Abe T, Murata H, Sagara Y, Sato H, Wada Y, Fuse N, Nakagawa Y, Tamai M, Nishida K. Hypothermia Protects Cultured Human Retinal Pigment Epithelial Cells against Indocyanine Green Toxicity. J Ocul Pharmacol Ther 2007; 23:35-9. [PMID: 17341148 DOI: 10.1089/jop.2006.0072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE The aim of this study was to determine whether indocyanine green (ICG) is toxic to cultured human retinal pigment epithelial (ARPE-19) cells, and whether hypothermia can protect the ARPE-19 cells against the ICG toxicity. METHODS Cultured ARPE-19 cells were exposed to 0.25, 0.5, 1, 2.5, and 5 mg/mL of ICG dye at 37 and 4 degrees C for 30 min. The percentage of ARPE-19 cells that survived was determined by resazurin 1 day after the exposure. RESULTS Exposure of the RPE cells to a hypotonic saline solution with an osmolarity equal to 5 mg/mL of ICG did not induce a statistically significant decrease in the percentage of RPE cells that survived. Exposure of the ARPE-19 cells to ICG induced a significant decrease in the percentage of cell survival at all concentrations of ICG (P<0.05), except in 0.25 mg/mL at 37 degrees C. At 4 degrees C, on the other hand, ICG induced a statistically significant decrease in the percentage of RPE cell survival only at 5 mg/mL of ICG (P<0.05). CONCLUSIONS These results indicate that ICG is toxic to human RPE cells in culture, and that cell death cannot be attributed to the low osmolarity. Hypothermia of 4 degrees C has a protective effect against ICG toxicity.
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Affiliation(s)
- Hiroshi Kunikata
- Department of Ophthalmology and Visual Science, Tohoku University Graduate School of Medicine, Sendai, and Ishinomaki Red Cross Hospital, Miyagi, Japan.
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Eliott D, Lee MS, Abrams GW. Proliferative Diabetic Retinopathy: Principles and Techniques of Surgical Treatment. Retina 2006. [DOI: 10.1016/b978-0-323-02598-0.50148-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Abstract
PURPOSE To study the effect of body temperature on the murine electroretinogram (ERG). METHODS The corneal ERG elicited by a strobe flash from dark-adapted mice was recorded using a saline wick electrode while measuring rectal temperature continuously. The mouse was placed within a cylindrical coil of tubing through which water circulated from a temperature controlled bath. The body temperature of the mouse was changed stepwise between 30 and 37 degrees C. RESULTS ERGs of approximately normal configuration were recorded at body temperature ranging between 30 and 37 degrees C. The maximum amplitude of the a- and b-waves varied linearly with temperature. The rate of change of b-wave amplitude was about 100 microV/degree. At 30 degrees C, maximum b-wave amplitude was about 400 microV; at 37 degrees C it was about 1000 microV. A change in body temperature produced a rapid change in ERG amplitude. CONCLUSION The murine ERG is very sensitive to changes in temperature. In order to monitor the ERG accurately over time, continuous recording of body temperature is essential.
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Affiliation(s)
- Jian Kong
- Department of Ophthalmology, Columbia University, New York, NY 10032, USA
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Findl O, Amon M, Kruger A, Petternel V, Schauersberger J. Effect of cooled intraocular irrigating solution on the blood-aqueous barrier after cataract surgery. J Cataract Refract Surg 1999; 25:566-8. [PMID: 10198865 DOI: 10.1016/s0886-3350(99)80057-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To evaluate the effect of cooled intraocular irrigating solution during phacoemulsification on postoperative blood-aqueous barrier (BAB) disturbance. SETTING Department of Ophthalmology, University of Vienna, Austria. METHODS In a prospective, randomized clinical study, 40 eyes with senile cataract had phacoemulsification with irrigating solutions cooled to approximately 10 degrees C (n = 20) or at room temperature (n = 20). Surgical procedure and postoperative therapy were otherwise identical in both groups. Postoperative BAB disturbance was assessed with the laser flare-cell meter on days 1, 3, 7, 14, and 28. RESULTS Anterior chamber flare was significantly lower in the group with cooled irrigating solution on postoperative day 1. There was no significant between-group difference in flare on any other postoperative day. CONCLUSION Cooled intraocular irrigating solution reduced immediate postoperative inflammation compared with irrigating solution at room temperature. However, this effect was of short duration.
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Affiliation(s)
- O Findl
- Department of Ophthalmology, University of Vienna, Austria
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Tamai K, Toumoto E, Majima A. Protective effects of local hypothermia in vitrectomy under fluctuating intraocular pressure. Exp Eye Res 1997; 65:733-8. [PMID: 9441696 DOI: 10.1006/exer.1997.0386] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of local hypothermia on the blood-aqueous barrier and retina were investigated in experimental vitrectomy under wide-ranging fluctuations of intraocular pressure. After anesthetized albino rabbits had undergone closed vitrectomy, their vitreous cavities were continuously irrigated for 60 minutes. Perfusion pressures were fluctuated alternately between 10 and 80 mmHg. The rabbits were divided into two groups in accordance with their intraocular perfusion temperatures: 8 degrees C and 22 degrees C. Electroretinograms were taken both before and after the irrigation. Protein and prostaglandin E2 (PGE2) concentrations in the aqueous humor were measured on the 1st and 7th postoperative days. Histologic examination was performed on the eyes enucleated on the same days. There were no significant differences in either a- or b-wave amplitudes between the 8 degrees C and 22 degrees C groups. Both aqueous protein and PGE2 concentrations were significantly higher in the 22 degrees C group than in the 8 degrees C group on the 1st postoperative day. Histologically, the ciliary body showed remarkably more stromal edema in the 22 degrees C group than in the 8 degrees C group. The severity of the retinal damage did not seem to differ between the two groups. Local hypothermia during vitrectomy under fluctuating intraocular pressure inhibits the breakdown of the blood-aqueous barrier in the early postoperative stages.
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Affiliation(s)
- K Tamai
- Department of Ophthalmology, Nagoya City University Medical School, Japan
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Tamai K, Toumoto E, Majima A. Local hypothermia protects the retina from ischaemic injury in vitrectomy. Br J Ophthalmol 1997; 81:789-94. [PMID: 9422935 PMCID: PMC1722302 DOI: 10.1136/bjo.81.9.789] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
AIMS Hypothermic irrigating solutions were used during vitrectomy in pressure induced ischaemic eyes so that their effects on retinal function and histological changes could be investigated. METHODS After anaesthetised albino rabbits underwent closed vitrectomy, their vitreous cavities were continuously irrigated for 30 minutes at a perfusion pressure of 140 mm Hg. The rabbits were divided into three groups according to their intraocular perfusion temperatures--8 degrees C, 22 degrees C, and 38 degrees C. Electroretinograms were taken before and after irrigation. Glutamate levels in the vitreous were examined after irrigation. Eyes were enucleated on the seventh postoperative day and examined histologically. RESULTS On the seventh postoperative day, the recovery rate of a-wave amplitudes was significantly lower in the 38 degrees C group than in the 8 degrees C group, and that of b-wave amplitudes was significantly lower in the 38 degrees C group than in either the 8 degrees C or 22 degrees C group. Retinal damage in the 38 degrees C group revealed more severe histological impairment than in either the 8 degrees C or 22 degrees C group. Oedema of the inner retinal layer was significant in both the 22 degrees C and 38 degrees C groups. Glutamates reached peak values 30 minutes after the end of ischaemia in the 38 degrees C group. However, no significant glutamate increases were detected 15 to 60 minutes after ischaemia in either the 8 degrees C or 22 degrees C group. CONCLUSION Local hypothermia during vitrectomy in acute ischaemic eyes appears to decrease retinal damage.
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Affiliation(s)
- K Tamai
- Department of Ophthalmology, Nagoya City University Medical School, Japan
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Lachapelle P, Benoit J, Guité P. The effect of in vivo retinal cooling on the electroretinogram of the rabbit. Vision Res 1996; 36:339-44. [PMID: 8746223 DOI: 10.1016/0042-6989(95)00126-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PURPOSE Studies reporting the effect of retinal cooling on the electroretinogram of mammals have, in most cases, made use of an in vitro approach where the temperature of the retina was lowered by reducing the temperature of the bathing media. The purpose of our study was to investigate, in rabbits, the effect of in vivo retinal cooling using an experimental approach never before reported in order to determine if some of the temperature-related ERG effects previously shown could have been, in part, amplified by alterations in the physiological status of the retina due to preparation for in vitro study. METHODS In order to reduce the temperature of the retina, a 20 gauge plastic tubing was coiled around the eye from the limbus to the optic nerve head and glued to the sclera. Cold (15 degrees C) tap water entered the tubing at the limbal extremity and exited (18 degrees C) at the optic nerve extremity. Intraretinal temperature was measured to be within 1 degrees C of that of the circulating water. RESULTS Our results indicate that with progressive retinal cooling the a- and b-waves are gradually reduced to 66.9 +/- 17.3 and 90.9 +/- 10.4% of control respectively. The most dramatic temperature induced ERG modifications were observed in the oscillatory potential recordings where the mean summed OP amplitude (OP2 + OP3 + OP4) was reduced to less than 23.9 +/- 13.5% of control with OP2 being the least affected. The peak times of all the ERG components were significantly delayed with cooling. CONCLUSIONS Of all the ERG components examined, the OPs were those most severely affected by our manipulation. We believe that our results constitute further evidence in support of the concept that the OPs are more sensitive to retinal disturbance than the b-wave.
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Affiliation(s)
- P Lachapelle
- Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
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Machemer R. The development of pars plana vitrectomy: a personal account. Graefes Arch Clin Exp Ophthalmol 1995; 233:453-68. [PMID: 8537019 DOI: 10.1007/bf00183425] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- R Machemer
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, USA
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Orgül S, Flammer J, Stümpfig D, Hendrickson P. Intraocular pressure decrease after local ocular cooling is underestimated by applanation tonometry. Int Ophthalmol 1995; 19:95-9. [PMID: 8586503 DOI: 10.1007/bf00133179] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND The effects of intense systemic or local cooling on aqueous humor dynamics in animals are an increased total outflow facility and a decreased aqueous flow. Few studies suggest that only vasoconstriction of arteriolar segments of the episcleral vasculature may be the cause for a decrease in intraocular pressure after local cooling in humans. Because corneal changes may have influenced such studies, the effect of local cooling was assessed in normal subjects. METHODS Intraocular pressure and corneal thickness were measured in 18 healthy human subjects before and after exposure of the right eye to both, an air stream at 20 degrees C, and an air stream at 0 degrees C. RESULTS No significant changes in IOP or corneal thickness occurred under 20 degrees C conditions. After local cooling, the mean corneal thickness increased from 0.52 +/- 0.01 mm to 0.57 +/- 0.02 mm (p < 0.001). Mean intraocular pressure decreased from 13.8 +/- 2.9 mmHg to 12.9 +/- 3.1 mmHg (p < 0.026). The observed decrease in IOP correlated significantly but negatively (R = -0.53; p = 0.024) with the increase in corneal thickness, indicating that the cooling effect on IOP may be rather underestimated. CONCLUSION The eye is very sensitive to local cooling effects, which may, however, partially be masked by changes in corneal thickness.
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Affiliation(s)
- S Orgül
- University Eye Clinic, Basel, Switzerland
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