Biomedical subjects

K S Morgan

Publications and source records attributed to K S Morgan.

At least 19 recordsLinked to original sources

PubMed1997

Off-axis photorefractive eye screening in children.

PURPOSE: To determine the utility of mass photoscreening for detecting visual anomalies in young, school-age children. SETTING: Seventy elementary schools in Alabama, Florida, Georgia, North Carolina, and Virginia, USA. METHODS: An off-axis photorefractive technique was used to screen 14,591 children in kindergarten, first, and fourth grades in 70 schools in 5 southeastern states in the United States. RESULTS: A total of 14,075 (96.5%) of the screenings yielded analyzable photographs. Overall, 647 (4.6%) children had significant ocular findings; significant was defined as hyperopia 2.50 diopters (D) or more, myopia 1.00 D or more, anisometropia 1.00 D or more, astigmatism 2.00 D or more, media opacity 1.0 mm or more in diameter, or 5 degrees or more or 10.00 prism diopters or more of ocular misalignment. Another 950 (6.7%) had possibly significant findings, defined as the sign being present but in an amount less than that considered significant. The most common refractive error was myopia (4.5%), followed by anisometropia (3.1%), hyperopia (2.9%), and astigmatism (1.0%). Alignment problems were found in 1.7% and media opacities in 0.1%. Among the 1.0% with other ocular anomalies were cases of anisocoria greater than 2.0 mm or irregular pupils, ptosis greater than 2.0 mm, and subconjunctival hemorrhages. In all, 202 children had significant anomalies thought to predispose to amblyopia, including 196 with significant anisometropia and 6 with significant lens opacities. At a screening cost of $5 per child for the whole study, the cost of identifying these children with potentially blinding eye disease was $361 each. CONCLUSION: Mass photoscreening may be used to detect amblyogenic conditions in children early enough to prevent blindness with timely and appropriate treatment.

Amblyopia↗

PubMed1995

Pediatric cataract and lens implantation.

Cataracts in children present a greater management challenge, compared with cataracts in adults, because of the wider variety of causes and the vulnerability of the developing visual system. The fundamental principles--early diagnosis and treatment for visually significant cataracts--have not changed. Amblyopia remains a major problem in children with unilateral and asymmetrical cataracts. The use of vitrectomy instrumentation in the removal of infantile cataracts has become relatively standard; however, the tendency now is to leave a rim of posterior capsule sufficient to allow secondary placement of a posterior chamber intraocular lens at a later date. Intraocular lens implantation is being aggressively pursued in children and, with modern microsurgical techniques, may be desirable in children as young as 2 years of age or younger in special circumstances. Contact lenses continue to be ideal for the infant and growing child to provide flexibility as the refraction changes.

Amblyopia↗

PubMed1993

Relationship between frequent episodes of peritonitis and altered immune status.

A 60-year-old Native American diabetic female patient had a history of nine episodes of peritonitis (both relapsing and persistent) during the year that she was treated with continuous ambulatory peritoneal dialysis (CAPD). At the start of CAPD the patient had an inverted CD4 to CD8 ratio that decreased from 0.97 to 0.50 in 1 year. This finding was due to a decrease in CD4+ cells and an increase in CD8+ cells that were also positive for CD57 (Leu-7) and HLA-DR (Ia) antigen, suggesting a state of activation. The serology indicated a cytomegalovirus immunoglobulin G titer of 1:2,048. The patient also had significantly increased natural killer cells. These alterations suggest the presence of a chronic viral infection that may have caused the patient to be immunosuppressed, thereby predisposing her to repeated episodes of peritonitis.

CD4-CD8 Ratio↗

PubMed1993

Cataract surgery and intraocular lens implantation in children.

As in the past, the current literature on childhood cataracts demonstrates the need for early diagnosis, surgical treatment that is quite different from adult cataract surgery, and prompt and adequate optical correction, as well as long-term and conscientious amblyopia therapy in cases of uniocular cataract. The choice of optical correction continues to generate controversy. Contact lenses, intraocular lenses, and epikeratophakia all have their advocates. Although contact lenses are still the most common option, interest in using intraocular lenses in children has grown. Over the past year, however, two disturbing reports of complications due to intraocular lens implants were published. Treatment of childhood cataracts remains more challenging than treatment of cataracts in adults, and indications for particular approaches to optical rehabilitation in the pediatric population continue to evolve.

Cataract↗

PubMed1989

Update on epikeratophakia in children.

Epikeratophakia continues to be an extremely attractive option for younger children with unilateral aphakia who are noncompliant users of contact lenses but who are young enough to benefit from amblyopia therapy. The epikeratophakia procedure is much safer than IOL implantation. The epikeratophakia tissue lens is especially useful for children with traumatic aphakia and corneal lacerations because the lens can strengthen and smooth the cornea as well as correct the aphakia. This allows much quicker rehabilitation than could be accomplished with contact lenses. The epikeratophakia procedure may be combined with a cataract extraction and should be in those children with acquired cataracts who demonstrate contact lens noncompliance in an office trial of contact lens insertion before operation. Epikeratophakia should be used with caution in neonates and young infants because of the rapid growth of the eye. Extended-wear contact lenses are a safer option for these children, and epikeratophakia can be performed as a secondary procedure if and when problems with contact lens compliance arise. Surface ocular problems such as uncontrolled dry eyes or severe blepharitis will continue to be incompatible with the survival of epikeratophakia tissue lenses. Children who are treated with high doses of radiation for orbital tumors such as rhabdomyosarcomas invariably develop radiation cataracts, which can occur before the onset of radiation keratitis. These children do not do well with epikeratophakia tissue lenses. Likewise, children with severe metabolic disturbances who are not healthy or gaining weight have a diminished chance of graft healing, as do children with poor vision in whom oculodigital autostimulation produces persistent epithelial defects, which prevent survival of the tissue lens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1988

Teller acuity cards versus clinical judgment in the diagnosis of amblyopia with strabismus.

Teller acuity card testing, which is a form of the preferential-looking procedure, is a popular way of assessing visual acuity in preverbal patients. The authors suspected that the clinical judgment of a pediatric ophthalmologist is superior to the Teller acuity cards in diagnosing amblyopia when strabismus is present. Acuity card and fixation preference measurements on each eye were compared at the same clinical visit in a group of 108 strabismic patients. The authors found that the acuity cards could be used to detect amblyopia. However, the pediatric ophthalmologist was more sensitive in diagnosing amblyopia than the Teller acuity cards in the presence of strabismus.

Amblyopia↗

PubMed1988

The nationwide study of epikeratophakia for aphakia in older children.

A nationwide study of epikeratophakia for aphakia in older children was conducted from March 1984 to March 1986. Sixty-three patients, 8 to 18 years of age, underwent this procedure in 65 eyes. Twenty-eight patients had congenital cataracts and 35 had traumatic cataracts. Fifty-one of the 65 eyes were aphakic at the time of surgery (secondary procedures). All surgeries were successful; no tissue lenses were lost or removed. Postoperatively, 73% of the patients were within 3 diopters (D) of emmetropia. The patients with congenital cataracts gained an average of one Snellen line of best-corrected visual acuity; patients with traumatic cataracts lost an average of one Snellen line of best-corrected visual acuity. In older pediatric patients, epikeratophakia appears to be a safe and effective procedure for the correction of aphakia.

Aphakia↗

PubMed1987

The nationwide study of epikeratophakia for aphakia in adults.

In the nationwide study of epikeratophakia, 154 ophthalmic surgeons who had attended a training course performed 519 procedures for the correction of aphakia in adults: 310 of the eyes had 30 or more days of follow-up after suture removal. Of 229 eyes, 172 (75%) were within 3 diopters of emmetropia after surgery. Of 259 eyes, 245 (95%) demonstrated improved uncorrected visual acuity; 138 (53%) improved by four or more Snellen lines. Of 265 eyes, 209 (78%) achieved within two lines or improved their best corrected visual acuity. Of the 119 patients who achieved or improved their preoperative best corrected visual acuity, 110 (92%) were within two Snellen lines or better by 30 to 60 days after suture removal. Of the 127 patients with more than three months of follow-up after suture removal, 124 (98%) of those between 18 and 70 years of age but only 13 of 23 (54%) of those between 81 and 87 years of age achieved within two lines or better of their best corrected visual acuity. Corneal astigmatism measured by keratometry changed from a preoperative mean (+/- S.D.) of 2.1 +/- 1.8 diopters to a postoperative mean of 2.7 +/- 2.6 diopters. Of the 519 tissue lenses, 22 (4%) were removed, and one third of these patients underwent a second, successful epikeratophakia procedure.

Adolescent↗

PubMed1987

The nationwide study of epikeratophakia for aphakia in children.

In the nationwide study of epikeratophakia, 97 surgeons performed a total of 335 procedures in 314 eyes for the correction of aphakia in children under the age of 8 years 1 month. Fifteen children underwent bilateral surgery. Thirty-six tissue lenses were removed and 21 of these eyes underwent a second epikeratophakia procedure. Overall, the success rate for procedures was 89%, and with repeated surgery it was 95% for eyes. Seventy-three percent of the patients were within 3 diopters of emmetropia after surgery. Visual acuity results in patients able to provide verbal responses to the illiterate E, Allen card, or Snellen line chart testing showed improvement in most cases. The safety of epikeratophakia makes it a desirable option for the correction of aphakia in children who are spectacle or contact-lens intolerant, and the permanence of the correction eliminates the problem of optical noncompliance.

Aphakia↗

PubMed1987

The nationwide study of epikeratophakia for myopia.

In the nationwide study of epikeratophakia, 116 ophthalmic surgeons performed 352 procedures for the correction of myopia; 256 of the eyes had 30 or more days of follow-up after suture removal. Of 204 eyes, 153 (75%) were within 30% of emmetropia after surgery. Of 208 eyes, 202 (97%) had postoperative best corrected visual acuity within two Snellen lines or better of their preoperative visual acuity. All but one patient improved uncorrected visual acuity. Of the 120 patients who equaled or improved their preoperative best corrected visual acuity, 116 (97%) were within two Snellen lines of their preoperative measurement between 30 and 60 days after suture removal. Corneal astigmatism changed from a preoperative mean (+/- S.D.) of 1.4 +/- 0.8 diopters to a postoperative mean of 2.6 +/- 2.1 diopters. Of 352 tissue lenses, 36 (10%) were removed, largely as a result of inaccurate power, decay, or failure to reepithelialize, and 17 of these eyes underwent a second successful epikeratophakia procedure.

Adolescent↗

PubMed1987

Clinical evaluation of a commercial photorefractor.

The Visiscreen 100 is a system designed to detect ocular anomalies photographically. Photorefractions obtained in 63 consecutive 3-month-old to 8-year-old patients were compared in a masked fashion with results obtained by conventional techniques, including cycloplegic refraction. In 87% of the 57 patients with analyzable photographs, photorefractive and examination results correlated for the detection of constant tropias. The photorefractor detected all ocular media opacities. In 77% of the cases, its refraction was within 2.5 diopters or 33% of the cycloplegic spherical equivalent. In detecting abnormal ocular status, the Visiscreen had a 91% sensitivity and a 74% specificity. The overall agreement rate in distinguishing abnormal from normal status was 84%. Most errors were related to inaccuracies in fixation and positioning, rather than the optical principles utilized. This device offers a rapid technique for the detection of factors predisposing preverbal children to amblyopia.

Child↗

PubMed1987

TCDD alters the extracellular matrix and basal lamina of the fetal mouse kidney.

The teratogenic effects of the dioxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have previously been studied in several species, and hydronephrosis has been reported to be a frequent abnormality in near-term fetuses. C57BL/6N female mice, given 12 micrograms/kg TCDD, P.O., on day 10 of gestation were killed on days 14, 15, and 16; fetal kidneys were collected and prepared for either immunofluorescent localization of several extracellular matrix components (ECM) or transmission electron microscopy (TEM). The TCDD-treated and control kidneys showed the same pattern of staining for fibronectin, but TCDD-treated kidneys displayed a diminished overall intensity. The intensity of laminin and type IV collagen immunofluorescence also appeared to be decreased, and deviations in the pattern of antibody binding were detected for differentiating TCDD-treated nephrons. Binding of the laminin antibody to the basal lamina was decreased in the parietal layer of Bowman's capsules in more advanced stages of differentiation. TEM analysis focused on the basal lamina of the tubules and Bowman's capsule. In TCDD-exposed kidneys, ECM components adjacent to differentiating nephrons were less abundant, and the basal lamina of the developing Bowman's capsules had a diminished lamina densa. The earliest nephrons to develop display these defects and comprise the first functional filtration units of the metanephric kidney. These ultrastructural changes noted in TCDD-exposed nephrons may promote proteinuria, a condition normally observed in the developing kidney when the filtration barrier is immature.

Abnormalities, Drug-Induced↗

PubMed1987

Prediction of aphakic refractive error in children.

Formulas created to predict the optical requirements of the aphakic eye have been tested mainly in adult eyes. The accuracy of these formulas in shorter pediatric aphakic eyes was examined using retrospective analysis of 17 aphakic pediatric patients. The Sanders-Retzlaff-Kraff contact lens formula, used previously to predict required lens powers for epikeratophakia, consistently underestimated the required aphakic correction in the shorter eyes, which may have been responsible in part for the large undercorrections obtained previously in patients under one year of age. The Hoffer-Colenbrander and Binkhorst theoretical formulas, Donzis-Kastl-Gordon percentage change formula, and a linear regression formula derived from the present data (LIN), were significantly more accurate. The differences between these formulas were not significant. The use of one of these formulas should facilitate prediction of required epikeratophakia lenticule power or intraocular lens power in young children.

Aphakia, Postcataract↗

PubMed1986

Long-term follow-up of refractive and keratometric results of pediatric epikeratophakia.

To examine the long-term stability of epikeratophakia and its effect on the development of young eyes, the change in corneal curvature and refractive error over time were reviewed in pediatric patients who underwent epikeratophakia for optical correction of aphakia. Over an average follow-up time of 28.0 months, corneal curvature flattened by 1.15 diopters, or 0.53 D/yr. The average change in refractive error was -2.81 D over 23.6 months, or 1.49 D/yr. Patients younger than 1 year of age at surgery became significantly more myopic over the period of follow-up (4.75 D) than patients older than 1 year of age at surgery (2.24 D). These changes are consistent with the corneal flattening and increase in axial length expected from normal growth. Aphakic infants corrected to emmetropia with epikeratophakia will likely require correction of myopia in later childhood.

Aphakia, Postcataract↗

PubMed1986

Interface opacities in epikeratophakia.

Although small, peripheral, cystic, or putty-gray infiltrates were observed along the suture tracks in 20 of 100 pediatric patients after epikeratophakia at Louisiana State University Medical Center, New Orleans, they progressed to clinically significant opacities in only three. In one, the interface material was curetted and the lenticule was reattached. The removed material was identified histologically as epithelial cells in varying states of degeneration. In a second case, the graft became hazy and the opacity involved most of the interface. The lenticule was removed, and epikeratophakia was again performed. On the posterior surface of the removed lenticule was a multilayered epithelium that had infiltrated into adjacent stromal lamellae. In the third case, a clear cyst resolved without intervention over a five-year period. These cases illustrate the importance of meticulous removal of all surface epithelium and the necessity for copious irrigation of epithelial debris intraoperatively. Epithelial ingrowth should not be confused with bacterial infection. Such opacities can be treated by curettage or aspiration of the invading material or removal of the epikeratophakia lenticule if spontaneous resolution does not occur.

Aphakia↗

PubMed1986

Effect of serum on cell-to-cell associations during in vitro development of preimplantation mouse embryos.

We have identified an activity which alters the morphology and developmental timing of post-compaction mouse embryos. A 15-min exposure of 4- and 8-cell mouse embryos to sera containing this activity induced monolayer formation, changing the normal positions of blastomeres at the 16- to 64-cell stages. Recovered embryos form normal blastocysts, based on morphology and in vitro production of trophectoderm and inner cell mass derivatives. These results suggest that under certain circumstances blastomeres remain developmentally labile as late as the sixth or seventh cleavage cycle.

Animals↗

PubMed1986

Five year follow-up of epikeratophakia in children.

Epikeratophakia alters the anterior curvature of the cornea by the addition of a machine-carved donor lenticule. Since March 1980, 88 patients under eight years of age have had epikeratophakia, with at least six months of follow-up. Eighty percent of the original surgeries were successful; some failed grafts were replaced successfully, so that in all, 89% of the patients had successful grafts. The average increase in curvature of the cornea was 14.7 diopters, and the average spectacle overcorrection was +0.56 diopters. In these growing eyes, we documented a myopic shift of 1.5 diopters per year. Visual acuity results varied with the timing of refractive surgery, density of the amblyopia, and the parents' ability to maintain the patching schedule. The largest group of children were those who had unilateral traumatic cataracts. In this group, 7 of 15 patients who had surgery under 4 years of age had final verbal acuities of 20/40 or better. Long-term follow-up has demonstrated that epikeratophakia safely and successfully corrects refractive errors in aphakic children either as a primary procedure, or as a secondary procedure after cataract extraction.

Cataract↗

PubMed1985

Keratometric and refractive results of pediatric epikeratophakia.

Keratometric and refractive results of pediatric epikeratophakia showed that patients under 1 year of age had steeper corneas preoperatively and required more correction, as estimated by the Sanders-Retzlaff-Kraff regression formula. The average spherical equivalent of refractive error six months postoperatively was +6.92 +/- 4.67 diopters in patients under 1 year, and -0.72 +/- 4.22 D in patients over 1 year. Three of 14 younger patients and 35 of 54 older patients were within 3 D of emmetropia. Since March 1982, significant undercorrection has occurred only in patients 6 months old or younger. Younger children achieved an average of 46% of the predicted change in corneal curvature, while older children achieved 85%. Also, the Sanders-Retzlaff-Kraff formula may be inaccurate in estimating powers for younger children. Therefore, we recommend at this time that epikeratophakia be used as a secondary procedure in neonates with congenital cataracts.

Age Factors↗