Biomedical subjects
Nick Mamalis
Publications and source records attributed to Nick Mamalis.
Persistent severe visual and electroretinographic abnormalities after intravenous Cisplatin therapy.
A 55-year-old man inadvertently received four times the intended dose of intravenous cisplatin as part of a chemotherapeutic salvage regimen for non-Hodgkin lymphoma. Immediately after treatment, he developed bilateral irreversible visual loss. Visual acuity was 20/300 in OU and visual fields showed central scotomas bilaterally. Although the fundus examination findings were normal, an electroretinogram showed markedly reduced a-wave amplitudes and absent b-waves. At autopsy 8 months later, photoreceptors appeared normal. Splitting of the outer plexiform layer was present, consistent with loss of the ERG b-wave. This is the first reported case of persistent visual loss from intravenous cisplatin toxicity and the first case to describe ocular histopathologic findings.
The "demise" of diagnostic and research ocular pathology: temporary or forever?
PURPOSE: Several authorities have documented a significant decrease in support for modern eye pathology/pathology research laboratories. Indeed, many laboratories have closed or suffered marked cutbacks. The purpose of this report is to ask why this is so and to seek a possible means for reversing this trend. METHODS: Observations from the senior author's experience and a case from author's facility are analyzed. RESULTS: There are several reasons for ocular pathologists' difficulties, such as financial problems, lack of vision, personality conflicts, and problems with the departmental administration. Until recently, most research and development in several subspecialty fields of ophthalmology, including biodevices research, has been done primarily by engineers and in-house workers in industry. This precludes proper independent, nonbiased control and guidance from academia. Most ocular pathologists have not participated in this relatively new and wide-open field. CONCLUSIONS: We suggest a new realm of activity for today's newly trained ocular pathologists. Based on personal experience of two decades of fruitful collaboration with industry, we believe that ocular pathologists are uniquely trained to apply their expertise to various new fields of research that most pathologists today have not utilized. An important example is research on clinicopathological aspects of implantable biodevices. In addition, support and oversight should be provided by the major ophthalmic societies, such as the American Academy of Ophthalmology, in order to retain (even regain) control over this field. This is mandatory in order to control the safety and efficacy of new drugs and devices being introduced almost daily. Only then can clear differentiation between profit and patient welfare be achieved as potentially dangerous devices and techniques are let loose on the market. The field of "routine, descriptive" eye pathology is severely wounded and will return only in an attenuated fashion. In general, full-time support for ocular pathologists will not be possible unless they seek extra support from the private sector, engage in a concurrent clinical practice, or are supported by an endowed chair (a wonderful alternative).
Intraocular lens biocompatibility.
Explore the source record for details and available documents.
In vitro comparison of glistening formation among hydrophobic acrylic intraocular lenses(1).
PURPOSE: To compare glistening formation induced by temperature stressing in vitro among hydrophobic acrylic intraocular lenses (IOLs) available in the United States. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: Wagon Wheel (WW) packaged 1-piece AcrySof IOLs (Alcon), WW-packaged 3-piece AcrySof IOLs, and Sensar IOLs (Allergan Medical Optics) were analyzed in vitro for 5 consecutive days. Ten IOLs of each type were inserted into viewing chambers filled with balanced salt solution, maintained at 37 degrees C, and evaluated every 24 hours at 37 degrees C and then, after a 2-hour cooling, at room temperature. The IOLs were examined by slitlamp to quantify glistenings and by digital photography to determine glistening size. RESULTS: The glistening quantity was minimal and did not differ among IOL types at 37 degrees C. The glistenings were smallest in the 1-piece AcrySof IOLs (P <.001): 6.3 microm versus 11.5 microm in the Sensar and 13.4 microm in the 3-piece AcrySof. Upon cooling, the glistening quantity increased dramatically in the 1-piece AcrySof IOLs (P <.008) and was the highest among the IOL types at room temperature (P <.001). The mean glistening size was 7.7 microm. The 3-piece AcrySof IOLs showed a significant decrease in slitlamp-countable glistenings but acquired a dense haze seen as minute glistenings (4.0 microm) at x80 magnification. The glistening quantity in the Sensar IOLs was fairly stable upon cooling; a statistical increase was seen on the last day (P =.007). Cooling nearly doubled the size of the Sensar glistenings, which were the largest at room temperature, 21.7 microm (P <.001). CONCLUSIONS: Glistening quantity varied among hydrophobic acrylic IOLs and was temperature dependent. Sensar IOLs were more stable than the 2 other IOL types. The glistening phenomenon must be studied further to eliminate the problem.
Interlenticular opacification of piggyback acrylic intraocular lenses.
A dense interlenticular opacification developed 18 months after cataract surgery in a hyperopic patient with 2 acrylic piggyback intraocular lenses (IOLs) placed in the capsular bag. The patient developed a hyperopic shift with decreased vision, requiring explantation of the lenses. The dense interlenticular opacification did not allow separation of the lenses intraoperatively because of the tight adherence of the 2 IOLs.
Three-year clinical comparison of 3-piece AcrySof and SI-40 silicone intraocular lenses.
PURPOSE: To compare the 3-year performance of the 3-piece AcrySof (Alcon) and the SI-40 silicone (Allergan) intraocular lenses (IOLs). SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: In this retrospective study, patients with no complications and at least a 3-year follow-up after IOL implantation were examined for signs of inflammation, visual function, posterior capsule opacification (PCO), and satisfaction. RESULTS: One hundred eleven patients were enrolled with equivalent visual acuity, inflammation, and PCO parameters. The AcrySof eyes had less anterior capsule opacification and more intralenticular inclusions than the other group. Complete anterior capsule overlap was associated with decreased PCO, and significantly more SI-40 eyes had complete anterior capsule overlap. CONCLUSIONS: The second-generation silicone IOL was equivalent to the 3-piece AcrySof in patient satisfaction, visual function, inflammation, and PCO. The amount of anterior capsule overlap on the IOL may help to explain the study differences.
OVDs. viscosurgical, viscoelastic, and viscoadaptive. What does this mean?
Explore the source record for details and available documents.
Complications of foldable intraocular lenses requiring explantation or secondary intervention--2001 survey update.
A survey of the complications associated with foldable intraocular lenses (IOLs) that required explantation or secondary intervention was sent to members of the American Society of Cataract and Refractive Surgery and the European Society of Cataract and Refractive Surgeons. Preoperative data about visual acuity, patient signs and symptoms, and complications requiring IOL removal were assessed. Postoperative results and outcomes were also analyzed. Complications and symptoms for each of the following major groups of foldable IOLs explanted were tabulated separately: 3-piece hydrophilic acrylic or hydrogel; 3-piece monofocal silicone; 3-piece hydrophobic acrylic; 1-piece hydrophobic acrylic with haptics; 3-piece multifocal silicone; 1-piece plate-type silicone. A total of 286 surveys were returned for evaluation. Intraocular lens calcification, incorrect lens power, optical visual aberrations, and decentration/dislocation were the most common reasons for removing a foldable IOL. Accurate IOL measurements, meticulous surgical technique, proper patient counseling, and careful manufacture of foldable IOL materials are the most important factors in avoiding complications with foldable IOLs.
Postoperative endophthalmitis.
Postoperative endophthalmitis is a rare, albeit serious, complication of cataract surgery. Over the years, preoperative and operative measures, such as lid hygiene, appropriate surgical draping, and improved surgical technique, have all decreased the incidence of postoperative endophthalmitis. Commonly used prophylactic measures include preoperative topical, intracameral, and postoperative topical antibiotics. Since the landmark study done by the endophthalmitis vitrectomy study group, treatment has usually consisted of intravitreal antibiotics with or without pars plana vitrectomy (depending on the patient population). In this review, we have focused on advances in the field of endophthalmitis within the last year. These include articles examining treatment and complications of diabetic patients and those with retinal detachments, bacterial adherence to lenses, prophylactic measures, and addition of steroids to conventional treatments of endophthalmitis.
Survey of intraocular lens material and design.
Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.
Experimental evaluation of ophthalmic devices and solutions using rabbit models.
OBJECTIVE: To analyze and compare the geometry of the anterior segment of rabbit and human eyes, with relevance for the evaluation of intraocular lenses, and to review rabbit models used in our laboratory for the evaluation of different ophthalmic devices and solutions. PROCEDURES: Fifteen rabbit and 15 human eyes (10 phakic and 5 pseudophakic/group) obtained postmortem were used. Anterior-posterior length, equatorial diameter, and white-to-white (corneal diameter) were measured with calipers. The eyes were then analyzed with a very high-frequency ultrasound (Artemis, Ultralink) for measurements of the anterior chamber depth, and anterior chamber and ciliary sulcus diameters. The capsular bag diameter was measured with calipers from a posterior view, and the diameter and thickness of the crystalline lenses were measured after their excision from the phakic eyes. RESULTS: Although the size of the rabbit eye is overall smaller than the size of the human eye, the dimensions of the anterior segment of rabbit eyes are generally larger. The differences between rabbit and human eyes were statistically significant (Wilcoxon rank sum test) in terms of anterior-posterior length, equatorial diameter, white-to-white measurements (P < 0.0001), anterior chamber diameter (P = 0.0004), ciliary sulcus diameter (P = 0.0012), and crystalline lens diameter and thickness (P = 0.0003). CONCLUSIONS: Experimental evaluation of design features of new phakic intraocular lenses in rabbit eyes may be inconclusive without adaptation of their size/design, contrary to the evaluation of new pseudophakic lenses by implantation in the capsular bag. The rabbit is a very valuable model for the experimental evaluation of different ophthalmic devices and solutions.