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Biomedical subjects

J P Gills

Publications and source records attributed to J P Gills.

At least 19 recordsLinked to original sources
PubMed2000

Piggyback intraocular lens implantation.

The piggyback method of implanting two intraocular lenses in one eye has been successfully expanded to address pseudophakic refractive error in normal eyes and eyes that have undergone post-penetrating keratoplasty. Piggyback implantation has been combined with the use of newly available minus-power lenses to provide appropriate power for a cataract patient with keratoconus, as well as to correct pseudophakic myopia. The phenomenon of increased depth of focus in piggybacks may be explained by a contact zone between the lenses. The late complication of inter-lenticular cellular growth with resultant hyperopic shift, opacification, and loss of vision has recently become a concern.

Humans↗
PubMed1999

Minus-power intraocular lenses to correct refractive errors in myopic pseudophakia.

PURPOSE: To evaluate the effectiveness of a secondary, piggyback, minus-power intraocular lens (IOL) to correct the refractive error in patients with myopic pseudophakia. METHODS: In this prospective noncomparative cohort study, 51 myopic pseudophakic patients received implantation of a minus-power IOL as a secondary procedure to correct residual pseudophakic myopia. RESULTS: The mean residual myopia of -3.05 diopters (D) was reduced to -0.38 D. All eyes were within +/- 1.00 D of the desired refraction. Uncorrected visual acuity was 20/40 or better in 72% of eyes, and best corrected visual acuity was 20/40 or better in 96%. Uncorrected visual acuity improved by 2 or more lines in 85% of eyes and by 5 or more lines in 65%. CONCLUSION: Clinical outcomes can now be improved in patients with myopic pseudophakia whose previous options (i.e., lens exchange or refractive surgery) were more traumatic or less predictable.

Aged↗
PubMed1998

Refractive and visual outcome of hyperopic cataract cases operated on before and after implementation of the Holladay II formula.

OBJECTIVE: The primary objective was to evaluate the refractive and visual outcomes in a series of hyperopic cataract cases in which the Holladay II intraocular lens (IOL) power formula was used in conjunction with added eye measurements (measured anterior chamber depth [ACD], lens thickness, and corneal diameter) to improve predictability of refractive outcome. In addition, the impact of use of a double ("piggyback") IOL on refractive outcome was evaluated. DESIGN: Prospective, nonrandomized comparative clinical trial. PARTICIPANTS: A total of 136 consecutive hyperopic primary cataract-IOL cases operated on at in an outpatient eye surgery center were evaluated. The main inclusion criterion was the requirement of at least 30 D of emmetropia power. INTERVENTION: Implantation of a total implanted power calculated using a newly developed (Holladay II) formula, which uses additional eye measurements (measured ACD, lens thickness, corneal diameter) in addition to the axial length and keratometry normally used, was performed. In the first series, IOL powers were chosen using the Lloyd-Gills formula with modifiers; in the second series, powers were chosen using the Holladay II formula option in the Holladay IOL Consultant software. Selection criteria for both series were the same (requiring at least 30 diopters [D] of power for emmetropia). Keratometry and axial length measurements (by immersion) were taken using the same instrumentation and methodology in both series. Predicted postoperative refraction based on the IOL implanted and the method of power calculation used were computed for each case in both groups and compared to the actual achieved refraction. MAIN OUTCOMES MEASUREMENTS: Main clinical outcome parameters evaluated were the postoperative spherical equivalent (compared with the predicted spherical equivalent) and the best-corrected vision. These outcome parameters were evaluated within each surgical series, in the total group of cases (regardless of power calculation method). Further stratification according to the use of single or double implants also was done. RESULTS: In the group using an older formula system, mean preoperative spherical equivalent of 4.79 D was reduced to -0.67 D. Similarly, in the Holladay II group, the preoperative mean of 5.60 D was reduced to -0.58 D. However, there were fewer large deviations between predicted and achieved spherical equivalent in the Holladay II group as indicated by a smaller standard deviation of the absolute deviation (0.47 vs. 0.59), and the range of postoperative refractions was smaller with fewer large overcorrections or undercorrections. However, almost 90% of both groups were within a diopter of the predicted refraction. Visual results were comparable in the two groups. CONCLUSION: Both IOL calculation systems showed good predictability in these extremely short eyes. The Holladay II formula was simpler because it is incorporated into a user-friendly software package (Holladay IOL Consultant) and required only the input of IOL constants and preoperative measurements with no "fudge factor" modifiers. Results within the series using this formula had a tendency toward a smaller standard deviation with fewer outliers.

Cataract Extraction↗
PubMed1998

Piggyback minus-power lens implantation in keratoconus.

A 53-year-old man with keratoconus and an axial length of 32.59 mm had cataract extraction by phacoemulsification. The Holladay II formula called for -14.00 diopters (D) of power. Two negative-power intraocular lenses (IOLs) were implanted to optimize visual results. A 1 day postoperative refraction of +1.50 D sphere necessitated an exchange of the anterior IOL. Six days after the exchange, the patient had a refraction of -1.25 D sphere and best corrected visual acuity of 20/50.

Eye↗
PubMed1998

Microtubule disruption leads to cellular contraction in human trabecular meshwork cells.

PURPOSE: To determine whether microtubule- and actin-altering drugs, which have been shown to increase aqueous humor outflow, cause cellular contraction in human trabecular meshwork (HTM) cells. METHODS: HTM cells were plated in culture dishes containing a polymerized deformable silicone substrate. After 48 hours, the dishes were placed on an inverted microscope and treated with ethacrynic acid, colchicine, vinblastine, cytochalasin B, or 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) and then recorded on videotape for 15 minutes. An increase in silicone substrate wrinkle size and/or number indicated a contraction. Sham controls were used. RESULTS: Cellular contraction was observed with ethacrynic acid, colchicine, and vinblastine in the 10(-5) to 10(-4) M dosage range. Pretreatment with H-7 blocked these effects. Cytochalasin B did not produce cellular contraction. CONCLUSIONS: Microtubule disruption causes cellular contraction in HTM cells, and this effect depends on an intact actin cytoskeleton network. Contraction of trabecular meshwork cells in response to various stimuli is an attractive hypothesis for possible homeostatic mechanisms in the outflow pathway, and this may serve as a focus for novel glaucoma drug development.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Unpreserved lidocaine to control discomfort during cataract surgery using topical anesthesia.

PURPOSE: To determine whether intraoperative unpreserved lidocaine further decrease discomfort or pain during sutureless small incision cataract surgery and intraocular lens (IOL) implantation under topical anesthesia. SETTING: Outpatient ambulatory surgical center. METHODS: In this prospective controlled study, comparable eligible patients were randomized to receive 0.1 cc unpreserved lidocaine 1% or 0.1 cc balanced salt solution (BSS) (control group) in double-masked fashion. Study drugs were injected intracamerally 1 minute before phacoemulsification. A predefined uniform pain/discomfort scale was used for assessment during phacoemulsification and IOL insertion. A secondary study using a 0.5 cc dose was also performed. RESULTS: Twenty-six percent in the control group and 9% in the lidocaine group had discomfort pain scores of 2 or more; 10% in the BSS group felt increased pressure or pain during phacoemulsification. In the lidocaine group, discomfort was felt mainly during IOL insertion, possibly as a result of wound manipulation. During phacoemulsification, no patient in the lidocaine group reported pain; 2% felt increased pressure during phacoemulsification. A dose increase to 0.5 cc reduced any intraocular sensation to 3% in the lidocaine group. No patient in either group had significant cell loss or adverse events. CONCLUSION: Intraoperative lidocaine is safe and effective in controlling intraoperative discomfort.

Aged↗
PubMed1996

Achieving emmetropia in extremely short eyes with two piggyback posterior chamber intraocular lenses.

PURPOSE: To examine the refractive results and limitations of current intraocular lens power formulas when implanting two posterior chamber lenses in-the-bag to achieve emmetropia in extremely short eyes. METHODS: Preoperative measurements (corneal diameter, axial length, keratometry, anterior chamber depth, and lens thickness) and postoperative measurements (refraction, corneal vertex to iris depth, and iris to front anterior lens surface) were taken in six eyes from three patients, with axial lengths ranging from 15.09 to 19.95 mm. These data were used to calculate the prediction error for three current third-generation formulas (Holladay, Hoffer Q, SRK/T) and two older formulas (SRK2 and SRK1). RESULTS: None of the formulas accurately predicted the refractions using the optimized lens constants for normal eyes. The third-generation formulas were not different (P > or = 0.602) and averaged 5 diopters (D) of absolute error (Hoffer Q = 4.64 +/- 1.57 D; Holladay = 5.07 +/- 1.28 D; SRK/T = 5.12 +/- 1.43 D). The older formulas were significantly worse (P = 0.0006), with average mean absolute errors of 10.93 +/- 5.09 D for the SRK2 and 13.33 +/- 5.09 D for the SRK1. When the formulas were optimized for these six eyes, the mean absolute errors were Holladay = 1.33 +/- 1.25 D; SRK/T = 2.10 +/- 1.31 D; Hoffer Q = 4.54 +/- 2.00 D; SRK2 = 4.71 +/- 1.94 D; and SRK1 = 4.71 +/- 1.94 D. The Holladay and SRK/T formulas were statistically better (P = 0.0068) than the Hoffer Q and the two older formulas. CONCLUSION: Current third-generation formulas are better than older formulas for extremely short eyes, but still are not acceptable for the desired clinical accuracy. Newer formulas that will use additional anterior segment measurements (corneal diameter, anterior chamber depth, and lens thickness) will be required for improved accuracy, because the anterior segment often is not proportional to the axial length.

Anterior Chamber↗
PubMed1995

Anesthesia, preoperative, and postoperative medications.

Retrobulbar and peribulbar anesthesia remain the principle means of ophthalmic anesthesia. Methods, needles, and medications continue to vary in the search for what works best, and that is a very individual preference as is seen by the literature over the past year. The increased role of nonsteroidal anti-inflammatory drugs is discussed, along with prophylactic antibiotic use.

Anesthesia, Local↗
PubMed1993

When keratometric measurements do not accurately reflect corneal topography.

The keratometer has been the standard for measuring corneal curvature for decades and until recently seemed sufficient for most clinical situations. However, it measures only four points from a small region of the cornea and assumes that the cornea is symmetrical. We document with a number of examples a variety of clinical cases in which keratometry provides either incomplete or frankly misleading information. We believe that corneal topography is now an invaluable clinical tool and will replace the keratometer in standard clinical practice.

Astigmatism↗