Rehab Ismail - Academia.edu (original) (raw)

Papers by Rehab Ismail

This chapter reviews complications associated wth cataract surgery and includes discussion of the... more This chapter reviews complications associated wth cataract surgery and includes discussion of their risk factors, clinical presentation, prevention and management strategies. For the sake of discussion these complications are classified into intraoperative, early postoperative and late postoperative complications. 2. Anaesthesia-related complications Ocular anaesthesia may be complicated by both ophthalmic and systemic factors. There have been reports of potentially life-threatening complications, including optic nerve damage, globe perforation as well as brainstem anaesthesia, dysrhythmias and cardiovascular depression. These complications are mainly seen with sharp needle techniques and are rarely encountered nowadays as cataract surgery is usually performed under topical or sub-Tenon's anaesthesia (1). 2.1 Optic nerve damage If a sharp needle accidently penetrates the dural sheath of the optic nerve (2), the anaesthetic can track back to the brainstem, causing unconsciousness and severe cardiorespiratory collapse/arrest with a potentially lethal outcome. This complication is rare, with some studies suggesting an incidence of between 0.09% and 0.79% for brainstem depression (3). Needle trauma to the optic nerve tissue can lead to significant loss of vision (4). 2.2 Globe perforation Globe perforation is a rare complication of sharp needle anaesthesia and has been reported with both retrobulbar and peribulbar approaches with an incidence of 0.009% to 0.13% (3). This complication has potential for causing severe injury to the retina and is more frequently encountered in highly myopic eyes and eyes that underwent scleral buckling for retinal detachment (2). Globe perforation should be suspected if hypotony is encountered after administering sharp needle anaesthesia. However, this could be absent if a large volume of anaesthetic has been injected intraocularly. Another sign is a dim red reflex and sometimes blood may be seen Cataract Surgery 222 behind the crystalline lens by the operating surgeon at the start of the operation. Management includes examination of the fundus to assess the extent of retinal damage and to apply argon laser photocoagulation or cryopexy to retinal breaks, if necessary(5). However, in most cases, examination of the fundus is usually difficult due to the presence of vitreous haemorrhage complicating the perforation. B scan ultrasonography is helpful in this context but vitrectomy surgery is usually indicated to remove the haemorrhage and deal with the retinal damage. Of note, in addition to the physical damage that could be caused by the needle injury to the globe, injection of the anaesthetic into the vitreous can also result in retinal toxicity and poor vision (6). 2.3 Retrobulbar haemorrhage Retrobulbar haemorrhage is an uncommon complication of ocular anaesthesia with an incidence of 0.032 to 3%. The condition is more common with sharp needle techniques (retrobulbar and peribulbar) compared to blunt needle anaesthesia (sub-Tenon's) (1) , and is more common in patients on antiplatelet medications and anticoagulants with elevated an International Normalised Ratio (INR) (5). Retrobulbar haemorrhage is an emergency condition that needs to be promptly dealt with to save vision. It usually presents shortly after administration of the anaesthetic injection with increasing proptosis, tightness of the lids, subconjunctival haemorrhage and elevated intraocular pressure (IOP) that can lead to occlusion in the central retinal artery or short post ciliary arteries and blindness (5). Initially mild intermittent compression on the globe can be helpful to stop further bleeding and limit progression of the haemorrhage. If this fails to resolve the condition, then pressure on the globe has to be relieved by performing a lateral canthotomy and cantholysis of the inferior crus of the lateral tarsal ligament. This is usually sufficient to decompress the orbit around the globe in most cases. IOP-lowering medications may be considered but these are usually not sufficient of their own to resolve pressure on the retinal circulation. Elective cataract surgery must be cancelled but may be rescheduled after at least a few weeks. While no immediate laboratory test is essential, patients must be reassessed to exclude underlying blood dyscrasias. Subsequent cataract surgery is better performed under topical anaesthesia and attention should be given to normalizing the INR level if elevated and stopping antiplatelet medications in liaison with a physician. 3. Surgery-related complications 3.1 Positive vitreous pressure Positive vitreous pressure can occur due to poor akinesia, inadvertent pressure on the globe from a tight lid speculum, proptosis, retrobulbar haemorrhage, eyelid abnormalities, as well as high hypermetropia. In this situation the iris-lens-diaphragm is pushed forward making surgery difficult and increasing the risk of more serious complications including iris damage, posterior capsule rupture and suprachoroidal haemorrhage (5). Positive vitreous pressure is best dealt with by early recognition. In many cases a tight lid speculum is the culprit and minor adjustment of the speculum can correct the problem. Should this fail, attention needs to be directed to other causes including retrobulbar haemorrhage that usually manifests before the start of the surgery or aqueous misdirection and suprachoroidal haemorrhage that will present later on during the surgery. In the absence of retrobulbar

Well established pathognomonic Optical Coherence Tomography (OCT) and Optical Coherence Tomograph... more Well established pathognomonic Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) findings for choroidal tumors are lacking. Purpose: To evaluate spectral domain OCT SD-OCT using choroidal enhancement technique (EDI) and more recently OCTA in detecting diagnostic criteria of choroidal tumors Methods: A multicenter observational study was conducted between 2007 and 2017 for recently diagnosed choroidal tumors using OCT and OCTA technology. Qualitative analysis included the overlying retina, tumor surface and internal features, light penetration within the mass (intra lesion reflectivity) by OCT, and surrounding blood vessel changes by OCTA, in addition to discrimination from surrounding choroidal tissue. Results: A total of 50 eyes were identified and included for analysis. These were clinically classified into: choroidal metastasis, choroidal hemangioma, choroidal melanoma, choroidal nevus. SD-OCT identified precise criteria for each tumor type, and distinguished tumor landmarks from the surrounding normal choroid. OCTA highlighted various changes to the surrounding and overlying blood vessels and was performed on a total of 12 eyes. Conclusion: SD-OCT and OCTA are efficient in detecting pathognomonic criteria for different types of choroidal tumors and can be used as a non-invasive diagnostic tools. Introduction Choroidal tumors are the most common intraocular tumors with severe impact on vision. There are various types including melanocytic nevi, melanomas, metastases, cavernous hemangioma and other less common tumors as lymphoma, neurilemmoma, leiomyoma and osteoma. Indirect ophthalmoscopy, fundus photography, and ultrasonography remain the main methods of diagnosis [1].

Journal of Glaucoma, 2015

Comparing the relative effectiveness of interventions across glaucoma trials can be problematic d... more Comparing the relative effectiveness of interventions across glaucoma trials can be problematic due to differences in definitions of outcomes. We sought to identify a key set of clinical outcomes and reach consensus on how best to measure them from the perspective of glaucoma experts. A 2-round electronic Delphi survey was conducted. Round 1 involved 25 items identified from a systematic review. Round 2 was developed based on information gathered in round 1. A 10-point Likert scale was used to quantify importance and consensus of outcomes (7 outcomes) and ways of measuring them (44 measures). Experts were identified through 2 glaucoma societies membership-the UK and Eire Glaucoma Society and the European Glaucoma Society. A Nominal Group Technique (NGT) followed the Delphi process. Results were analyzed using descriptive statistics. A total of 65 participants completed round 1 out of 320; of whom 56 completed round 2 (86%). Agreement on the importance of outcomes was reached on 48/51 items (94%). Intraocular pressure (IOP), visual field (VF), safety, and anatomic outcomes were classified as highly important. Regarding methods of measurement of IOP, "mean follow-up IOP" using Goldmann applanation tonometry achieved the highest importance, whereas for evaluating VFs "global index mean deviation/defect (MD)" and "rate of VF progression" were the most important. Retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) was identified as highly important. The NGT results reached consensus on "change of IOP (mean of 3 consecutive measurements taken at fixed time of day) from baseline," change of VF-MD values (3 reliable VFs at baseline and follow-up visit) from baseline, and change of RNFL thickness (2 good quality OCT images) from baseline. Consensus was reached among glaucoma experts on how best to measure IOP, VF, and anatomic outcomes in glaucoma randomized controlled trials.

Journal of Glaucoma, 2013

In clinical trials, the selection of appropriate outcomes is crucial for the assessment of whethe... more In clinical trials, the selection of appropriate outcomes is crucial for the assessment of whether one intervention is better than another. Selection of inappropriate outcomes can compromise the utility of a trial. However, the process of selecting the most suitable outcomes to include can be complex. Ideally, glaucoma trials aim to evaluate important outcomes for clinicians and patients. A high variability in the selection of outcomes suggests that there is no consensus on how best to evaluate the effect of glaucoma interventions. Further, it makes evidence synthesis difficult. The purpose of this review is to determine the extent of clinical outcome measures used in published glaucoma Cochrane Reviews and Protocols. A systematic review was conducted (up to February 2012) of all Cochrane Reviews and Protocols related to glaucoma interventions and published in English language. All clinical, patient-reported, as well as economic outcomes were included. In the Cochrane Library there were 12 Reviews and 9 Protocols on glaucoma. A total of 118 clinical outcomes were reported. Intraocular pressure was the most commonly used clinical outcome (n=40), and it was used in 11 Reviews and 5 Protocols. Intraocular pressure was evaluated in many different ways; the most common one was a composite definition of success. Safety outcomes were also frequently reported. Visual field progression or change was reported in 6 reviews and 3 protocols, but in 13 different ways. Patient-reported quality-of-life measures were chosen as main outcome measure in 1 Review. There is a large variability in outcomes selected in glaucoma Cochrane Reviews and Protocols. This heterogeneity in outcome selection impairs the ability for evidence synthesis. There is an urgent need for standardization of outcomes used in glaucoma trials.

British Journal of Ophthalmology, 2014

In randomised clinical trials (RCTs) the selection of appropriate outcomes is crucial to the asse... more In randomised clinical trials (RCTs) the selection of appropriate outcomes is crucial to the assessment of whether one intervention is better than another. The purpose of this review is to identify different clinical outcomes reported in glaucoma trials. Methods We conducted a systematic review of glaucoma RCTs. A sample or selection of glaucoma trials were included bounded by a time frame (between 2006 and March 2012). Only studies in English language were considered. All clinical measured and reported outcomes were included. The possible variations of clinical outcomes were defined prior to data analysis. Information on reported clinical outcomes was tabulated and analysed using descriptive statistics. Other data recorded included type of intervention and glaucoma, duration of the study, defined primary outcomes, and outcomes used for sample size calculation, if nominated. Results The search strategy identified 4323 potentially relevant abstracts. There were 315 publications retrieved, of which 233 RCTs were included. A total of 967 clinical measures were reported. There were large variations in the definitions used to describe different outcomes and their measures. Intraocular pressure (IOP) was the most commonly reported outcome (used in 201 RCTs, 86%) with a total of 422 measures (44%). Safety outcomes were commonly reported, in 145 RCTs (62%) whereas visual field outcomes were utilised in 38 RCTs (16%). Conclusions There is a large variation in the reporting of clinical outcomes in glaucoma RCTs. This lack of standardisation may impair the ability to evaluate the evidence of glaucoma interventions.

British Journal of Ophthalmology, 2011

This chapter reviews complications associated wth cataract surgery and includes discussion of the... more This chapter reviews complications associated wth cataract surgery and includes discussion of their risk factors, clinical presentation, prevention and management strategies. For the sake of discussion these complications are classified into intraoperative, early postoperative and late postoperative complications. 2. Anaesthesia-related complications Ocular anaesthesia may be complicated by both ophthalmic and systemic factors. There have been reports of potentially life-threatening complications, including optic nerve damage, globe perforation as well as brainstem anaesthesia, dysrhythmias and cardiovascular depression. These complications are mainly seen with sharp needle techniques and are rarely encountered nowadays as cataract surgery is usually performed under topical or sub-Tenon's anaesthesia (1). 2.1 Optic nerve damage If a sharp needle accidently penetrates the dural sheath of the optic nerve (2), the anaesthetic can track back to the brainstem, causing unconsciousness and severe cardiorespiratory collapse/arrest with a potentially lethal outcome. This complication is rare, with some studies suggesting an incidence of between 0.09% and 0.79% for brainstem depression (3). Needle trauma to the optic nerve tissue can lead to significant loss of vision (4). 2.2 Globe perforation Globe perforation is a rare complication of sharp needle anaesthesia and has been reported with both retrobulbar and peribulbar approaches with an incidence of 0.009% to 0.13% (3). This complication has potential for causing severe injury to the retina and is more frequently encountered in highly myopic eyes and eyes that underwent scleral buckling for retinal detachment (2). Globe perforation should be suspected if hypotony is encountered after administering sharp needle anaesthesia. However, this could be absent if a large volume of anaesthetic has been injected intraocularly. Another sign is a dim red reflex and sometimes blood may be seen Cataract Surgery 222 behind the crystalline lens by the operating surgeon at the start of the operation. Management includes examination of the fundus to assess the extent of retinal damage and to apply argon laser photocoagulation or cryopexy to retinal breaks, if necessary(5). However, in most cases, examination of the fundus is usually difficult due to the presence of vitreous haemorrhage complicating the perforation. B scan ultrasonography is helpful in this context but vitrectomy surgery is usually indicated to remove the haemorrhage and deal with the retinal damage. Of note, in addition to the physical damage that could be caused by the needle injury to the globe, injection of the anaesthetic into the vitreous can also result in retinal toxicity and poor vision (6). 2.3 Retrobulbar haemorrhage Retrobulbar haemorrhage is an uncommon complication of ocular anaesthesia with an incidence of 0.032 to 3%. The condition is more common with sharp needle techniques (retrobulbar and peribulbar) compared to blunt needle anaesthesia (sub-Tenon's) (1) , and is more common in patients on antiplatelet medications and anticoagulants with elevated an International Normalised Ratio (INR) (5). Retrobulbar haemorrhage is an emergency condition that needs to be promptly dealt with to save vision. It usually presents shortly after administration of the anaesthetic injection with increasing proptosis, tightness of the lids, subconjunctival haemorrhage and elevated intraocular pressure (IOP) that can lead to occlusion in the central retinal artery or short post ciliary arteries and blindness (5). Initially mild intermittent compression on the globe can be helpful to stop further bleeding and limit progression of the haemorrhage. If this fails to resolve the condition, then pressure on the globe has to be relieved by performing a lateral canthotomy and cantholysis of the inferior crus of the lateral tarsal ligament. This is usually sufficient to decompress the orbit around the globe in most cases. IOP-lowering medications may be considered but these are usually not sufficient of their own to resolve pressure on the retinal circulation. Elective cataract surgery must be cancelled but may be rescheduled after at least a few weeks. While no immediate laboratory test is essential, patients must be reassessed to exclude underlying blood dyscrasias. Subsequent cataract surgery is better performed under topical anaesthesia and attention should be given to normalizing the INR level if elevated and stopping antiplatelet medications in liaison with a physician. 3. Surgery-related complications 3.1 Positive vitreous pressure Positive vitreous pressure can occur due to poor akinesia, inadvertent pressure on the globe from a tight lid speculum, proptosis, retrobulbar haemorrhage, eyelid abnormalities, as well as high hypermetropia. In this situation the iris-lens-diaphragm is pushed forward making surgery difficult and increasing the risk of more serious complications including iris damage, posterior capsule rupture and suprachoroidal haemorrhage (5). Positive vitreous pressure is best dealt with by early recognition. In many cases a tight lid speculum is the culprit and minor adjustment of the speculum can correct the problem. Should this fail, attention needs to be directed to other causes including retrobulbar haemorrhage that usually manifests before the start of the surgery or aqueous misdirection and suprachoroidal haemorrhage that will present later on during the surgery. In the absence of retrobulbar

Well established pathognomonic Optical Coherence Tomography (OCT) and Optical Coherence Tomograph... more Well established pathognomonic Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) findings for choroidal tumors are lacking. Purpose: To evaluate spectral domain OCT SD-OCT using choroidal enhancement technique (EDI) and more recently OCTA in detecting diagnostic criteria of choroidal tumors Methods: A multicenter observational study was conducted between 2007 and 2017 for recently diagnosed choroidal tumors using OCT and OCTA technology. Qualitative analysis included the overlying retina, tumor surface and internal features, light penetration within the mass (intra lesion reflectivity) by OCT, and surrounding blood vessel changes by OCTA, in addition to discrimination from surrounding choroidal tissue. Results: A total of 50 eyes were identified and included for analysis. These were clinically classified into: choroidal metastasis, choroidal hemangioma, choroidal melanoma, choroidal nevus. SD-OCT identified precise criteria for each tumor type, and distinguished tumor landmarks from the surrounding normal choroid. OCTA highlighted various changes to the surrounding and overlying blood vessels and was performed on a total of 12 eyes. Conclusion: SD-OCT and OCTA are efficient in detecting pathognomonic criteria for different types of choroidal tumors and can be used as a non-invasive diagnostic tools. Introduction Choroidal tumors are the most common intraocular tumors with severe impact on vision. There are various types including melanocytic nevi, melanomas, metastases, cavernous hemangioma and other less common tumors as lymphoma, neurilemmoma, leiomyoma and osteoma. Indirect ophthalmoscopy, fundus photography, and ultrasonography remain the main methods of diagnosis [1].

Journal of Glaucoma, 2015

Comparing the relative effectiveness of interventions across glaucoma trials can be problematic d... more Comparing the relative effectiveness of interventions across glaucoma trials can be problematic due to differences in definitions of outcomes. We sought to identify a key set of clinical outcomes and reach consensus on how best to measure them from the perspective of glaucoma experts. A 2-round electronic Delphi survey was conducted. Round 1 involved 25 items identified from a systematic review. Round 2 was developed based on information gathered in round 1. A 10-point Likert scale was used to quantify importance and consensus of outcomes (7 outcomes) and ways of measuring them (44 measures). Experts were identified through 2 glaucoma societies membership-the UK and Eire Glaucoma Society and the European Glaucoma Society. A Nominal Group Technique (NGT) followed the Delphi process. Results were analyzed using descriptive statistics. A total of 65 participants completed round 1 out of 320; of whom 56 completed round 2 (86%). Agreement on the importance of outcomes was reached on 48/51 items (94%). Intraocular pressure (IOP), visual field (VF), safety, and anatomic outcomes were classified as highly important. Regarding methods of measurement of IOP, "mean follow-up IOP" using Goldmann applanation tonometry achieved the highest importance, whereas for evaluating VFs "global index mean deviation/defect (MD)" and "rate of VF progression" were the most important. Retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) was identified as highly important. The NGT results reached consensus on "change of IOP (mean of 3 consecutive measurements taken at fixed time of day) from baseline," change of VF-MD values (3 reliable VFs at baseline and follow-up visit) from baseline, and change of RNFL thickness (2 good quality OCT images) from baseline. Consensus was reached among glaucoma experts on how best to measure IOP, VF, and anatomic outcomes in glaucoma randomized controlled trials.

Journal of Glaucoma, 2013

In clinical trials, the selection of appropriate outcomes is crucial for the assessment of whethe... more In clinical trials, the selection of appropriate outcomes is crucial for the assessment of whether one intervention is better than another. Selection of inappropriate outcomes can compromise the utility of a trial. However, the process of selecting the most suitable outcomes to include can be complex. Ideally, glaucoma trials aim to evaluate important outcomes for clinicians and patients. A high variability in the selection of outcomes suggests that there is no consensus on how best to evaluate the effect of glaucoma interventions. Further, it makes evidence synthesis difficult. The purpose of this review is to determine the extent of clinical outcome measures used in published glaucoma Cochrane Reviews and Protocols. A systematic review was conducted (up to February 2012) of all Cochrane Reviews and Protocols related to glaucoma interventions and published in English language. All clinical, patient-reported, as well as economic outcomes were included. In the Cochrane Library there were 12 Reviews and 9 Protocols on glaucoma. A total of 118 clinical outcomes were reported. Intraocular pressure was the most commonly used clinical outcome (n=40), and it was used in 11 Reviews and 5 Protocols. Intraocular pressure was evaluated in many different ways; the most common one was a composite definition of success. Safety outcomes were also frequently reported. Visual field progression or change was reported in 6 reviews and 3 protocols, but in 13 different ways. Patient-reported quality-of-life measures were chosen as main outcome measure in 1 Review. There is a large variability in outcomes selected in glaucoma Cochrane Reviews and Protocols. This heterogeneity in outcome selection impairs the ability for evidence synthesis. There is an urgent need for standardization of outcomes used in glaucoma trials.

British Journal of Ophthalmology, 2014

In randomised clinical trials (RCTs) the selection of appropriate outcomes is crucial to the asse... more In randomised clinical trials (RCTs) the selection of appropriate outcomes is crucial to the assessment of whether one intervention is better than another. The purpose of this review is to identify different clinical outcomes reported in glaucoma trials. Methods We conducted a systematic review of glaucoma RCTs. A sample or selection of glaucoma trials were included bounded by a time frame (between 2006 and March 2012). Only studies in English language were considered. All clinical measured and reported outcomes were included. The possible variations of clinical outcomes were defined prior to data analysis. Information on reported clinical outcomes was tabulated and analysed using descriptive statistics. Other data recorded included type of intervention and glaucoma, duration of the study, defined primary outcomes, and outcomes used for sample size calculation, if nominated. Results The search strategy identified 4323 potentially relevant abstracts. There were 315 publications retrieved, of which 233 RCTs were included. A total of 967 clinical measures were reported. There were large variations in the definitions used to describe different outcomes and their measures. Intraocular pressure (IOP) was the most commonly reported outcome (used in 201 RCTs, 86%) with a total of 422 measures (44%). Safety outcomes were commonly reported, in 145 RCTs (62%) whereas visual field outcomes were utilised in 38 RCTs (16%). Conclusions There is a large variation in the reporting of clinical outcomes in glaucoma RCTs. This lack of standardisation may impair the ability to evaluate the evidence of glaucoma interventions.

British Journal of Ophthalmology, 2011