Exposing the LASIK Scam

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 Post subject: Corneal nerve damage
PostPosted: Fri Nov 25, 2005 2:18 pm 
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http://www.ncbi.nlm.nih.gov/entrez/quer ... query_hl=9

Invest Ophthalmol Vis Sci. 2004 Nov;45(11):3991-6.

Corneal reinnervation after LASIK: prospective 3-year longitudinal study.

Calvillo MP, McLaren JW, Hodge DO, Bourne WM.

Department of Ophthalmology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.

PURPOSE: To measure the return of innervation to the cornea during 3 years after LASIK.

METHODS: Seventeen corneas of 11 patients who had undergone LASIK to correct myopia from -2.0 D to -11.0 D were examined by confocal microscopy before surgery, and at 1, 3, 6, 12, 24, and 36 months after surgery. In all available scans, the number of nerve fiber bundles and their density (visible length of nerve per frame area), orientation (mean angle), and depth in the cornea were measured.

RESULTS: The number and density of subbasal nerves decreased >90% in the first month after LASIK. By 6 months these nerves began to recover, and by 2 years they reached densities not significantly different from those before LASIK. Between 2 and 3 years they decreased again, so that at 3 years the numbers remained <60% of the pre-LASIK numbers (P <0.001). In the stromal flap most nerve fiber bundles were also lost after LASIK, and these began recovering by the third month, but by the third year they did not reach their original numbers (P <0.001). In the stromal bed (posterior to the LASIK flap interface), there were no significant changes in nerve number or density. As the subbasal nerves returned, their mean orientation did not change from the predominantly vertical orientation before LASIK. Nerve orientation in the stromal flap and the stromal bed also did not change.

CONCLUSIONS: Both subbasal and stromal corneal nerves in LASIK flaps recover slowly and do not return to preoperative densities by 3 years after LASIK. The numbers of subbasal nerves appear to decrease between 2 and 3 years after LASIK. The orientation of the regenerated subbasal nerves remains predominantly vertical.


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 Post subject: LASIK nerve damage symptoms persist at 16 months
PostPosted: Mon Dec 26, 2005 6:35 pm 
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LASIK nerve damage symptoms persist at 16 months


http://www.ncbi.nlm.nih.gov/entrez/quer ... &DB=pubmed

Ophthalmology. 2001 Jul;108(7):1230-5

Effects of laser in situ keratomileusis on tear production, clearance, and the ocular surface.

Battat L, Macri A, Dursun D, Pflugfelder SC.
Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, USA.

Excerpts from the full text:

? Corneal sensation remained reduced 16 months after LASIK

? Conjunctival sensation remained reduced 16 months after LASIK

? Tear clearance remained reduced 16 months after LASIK.

ABSTRACT

PURPOSE: To evaluate components of the integrated ocular surface/lacrimal gland unit in a series of patients before and after undergoing bilateral laser in situ keratomileusis (LASIK).

DESIGN: Prospective, noncomparative case series. PARTICIPANTS: Forty-eight eyes of 14 men and 34 women (age range, 26-54; mean, 39.2 years) who underwent bilateral LASIK for myopia or myopic astigmatism.

METHODS: LASIK was performed using a VISX Star Excimer Laser (Santa Clara, CA). Patients completed a questionnaire containing 11 questions that evaluated the character and severity of ocular irritation symptoms. Snellen visual acuity, tear fluorescein clearance, corneal fluorescein staining, aqueous tear production by the Schirmer 1 test, and corneal and conjunctival sensitivity were measured in each eye. Corneal surface regularity (SRI) was evaluated with the Tomey TMS-1 (Tomey, Cambridge, MA) topography instrument. Each randomly chosen eye was evaluated 1 to 2 days (T0) before LASIK and 7 days (T1), 1 (T2), 2 (T3), 6 (T4), 12 (T5), and 16 (T6) months postoperatively. A Wilcoxon test, two-tailed paired t test, Friedman test, or analysis of variance were used for statistical comparisons.

MAIN OUTCOME MEASURES: Components of the integrated ocular surface/lacrimal gland unit. RESULTS: Both corneal and conjunctival sensitivity were noted to be significantly decreased from preoperative levels at 1week, 1 month, 12 months, and 16 months postoperatively (P < 0.0002 at each time point). Symptom severity scores were significantly increased at 1 week, 12 months, and 16 months postoperatively (P < 0.007 at all time points). The mean Schirmer 1 test scores were 24 +/- 14 mm preoperatively, and they decreased to 18 +/- 14 mm by 1 month postoperatively (P < 0.001). Tear fluorescein clearance showed a linear increase postoperatively and was significantly greater than baseline (P < 0.001) at each time point. There was a significant increase in punctate corneal fluorescein staining at 1 week postoperatively (P < 0.0001), but staining returned to baseline by 12 months. There was a statistically significant increase in SRI 1 week postoperatively (P < 0.007) with return to baseline levels by 6 months.

CONCLUSIONS: Sensory denervation of the ocular surface after bilateral LASIK disrupts ocular surface tear dynamics and causes irritation symptoms. Patients undergoing LASIK should be informed of these risks.


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 Post subject:
PostPosted: Sat Mar 25, 2006 6:09 pm 
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Eye Contact Lens. 2006 Mar;32(2):88-93.


Evaluation of Corneal Sensitivity to Mechanical and Chemical Stimuli After LASIK: A Pilot Study.

Stapleton F, Hayward KB, Bachand N, Trong PH, Teh DW, Deng KM, Yang EI, Kelly SL, Lette M, Robinson D.

From the Cornea and Contact Lens Research Unit (F.S., K.B.H., N.B., P.H.T., D.W.H.T., K.M.Y.D., E.I.H.Y.), School of Optometry and Vision Science and Vision Cooperative Research Centre, University of New South Wales, Sydney, Australia; and Sydney Laser and Vision Centre (S.L.K., M.L., D.R.), Bondi Junction, Australia.

PURPOSE.: To evaluate the effect of laser in situ keratomileusis (LASIK) on corneal sensitivity, nerve morphology, and tear film characteristics.

METHODS.: A cross-sectional study design was used. Eighteen patients (eight men and 10 women with a mean age of 36.9 +/- 11.2 years) who had undergone bilateral LASIK for low myopia within 18 months of the study and 28 control subjects (16 men and 12 women with a mean age of 27.2 +/- 7.7 years) were enrolled. Central and inferior corneal thresholds to mechanical (air) and chemical (air plus carbon dioxide) stimuli were determined by using a staircase technique. Stimuli of a 1-second duration at 34 degrees C were delivered with a CRCERT-Belmonte aesthesiometer. Images of subbasal nerves in the central cornea were captured with confocal microscopy. Nerve morphology was classified as no nerves, short nerves (<175 mum), or long nerves (>175 mum), with or without interconnections. Noninvasive tear break up time was measured. The phenol red thread test was used to indicate basal tear secretion. Differences between groups were evaluated with analysis of variance, and associations between variables were evaluated with parametric or nonparametric correlation, when appropriate.

RESULTS.: Central corneal mechanical sensitivity was significantly reduced in the post-LASIK group compared with the control subjects (P<0.001). Nerve morphology was associated with mechanical threshold. Nerve morphology, mechanical sensitivity, and tear breakup time improved during the first 1 to 3 months after surgery, with little change thereafter. Chemical sensitivity was associated with tear secretion (P<0.05).

CONCLUSIONS.: Central corneal mechanical sensitivity is reduced in patients after LASIK, with partial recovery seen 3 months after surgery. A similar recovery trend is seen for nerve morphology.

_________________
Broken Eyes

"The price good men pay for indifference to public affairs is to be ruled by evil men." Plato


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 Post subject:
PostPosted: Mon Jun 19, 2006 12:30 pm 
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Am J Ophthalmol. 2006 Jun;141(6):1009-1015.e1.


Comparison of Corneal Nerve Regeneration and Sensitivity Between LASIK and Laser Epithelial Keratomileusis (LASEK).

Lee SJ, Kim JK, Seo KY, Kim EK, Lee HK.

Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.

PURPOSE: To compare changes in corneal nerve fibers and keratocyte density by confocal microscopy after laser-assisted in situ keratomileusis (LASIK) and laser epithelial keratomileusis (LASEK).

DESIGN: Prospective, nonrandomized comparative clinical trial.

METHODS: Fifty-six eyes of 28 patients who underwent LASIK and 52 eyes of 26 patients who underwent LASEK were included. Confocal microscopic data of the central cornea, corneal sensitivity, tear film breakup time, and Schirmer values were determined at three and six months after LASIK or LASEK treatment.

RESULTS: In the LASIK group, corneal sensitivity was reduced from preoperative levels at six months after surgery. In the LASEK group, however, there was no difference between baseline and six-month postoperative values. The number of subbasal nerve fibers and the keratocyte density were also different in the LASIK and LASEK groups. The regeneration of corneal nerves correlated strongly with the recovery of corneal sensation and keratocyte density in both groups, whereas the tear film breakup time, Schirmer values, and epithelial thickness did not correlate with corneal nerve regeneration in either group.

CONCLUSIONS: The greater decrease in the number of subbasal nerve fibers in the LASIK group compared with the LASEK group may relate to the greater decrease in corneal sensitivity. The pattern of corneal nerve regeneration and the recovery of corneal sensation after LASEK did not differ greatly from that after photorefractive keratectomy in previous studies.

_________________
Broken Eyes

"The price good men pay for indifference to public affairs is to be ruled by evil men." Plato


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PostPosted: Sun Jan 07, 2007 2:50 am 
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Invest Ophthalmol Vis Sci. 2002 Dec;43(12):3660-4.

Reinnervation in the cornea after LASIK.Lee BH, McLaren JW, Erie JC, Hodge DO, Bourne WM.

Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA.

PURPOSE: Nerve fibers in the cornea are disrupted by photorefractive procedures. In this study, the denervation and reinnervation of human central corneas were evaluated by sequential, quantitative measurements of nerves viewed by confocal microscopy in vivo during the first year after LASIK.

METHODS: Seventeen eyes were studied of 11 patients who had undergone LASIK to correct myopia from -2.0 D to -11.0 D. Eyes were treated with an excimer laser with a planned 180- micro m flap. Central corneas were scanned throughout their full thicknesses by confocal microscopy before and at 1 week and 1, 3, 6, and 12 months after LASIK. Nerve fiber bundles appeared as bright, well-defined, linear structures that were sometimes branched and usually appeared in several consecutive frames. The number of nerve fiber bundles per scan in two to eight scans per eye per visit was determined in the subbasal region, the full-thickness stroma, the stromal flap (layer between the most anterior keratocyte and the flap interface), and the stromal bed (layer between the flap interface and the endothelium).

RESULTS: In the subbasal region, the number of nerve fiber bundles decreased by more than 90% 1 week after LASIK and was significantly lower at all times after surgery than it was before surgery (P < 0.001). It increased 6 and 12 months after LASIK, but remained less than half of the preoperative value. In the stromal flap, the number of nerves at all times after surgery was also significantly less than before surgery (P < 0.001) and did not increase significantly by 1 year. In the stromal bed, there were no significant differences among any of the nerve measurements before and after LASIK (P = 0.24).

CONCLUSIONS: In the corneal flap, the number of subbasal and stromal nerve fiber bundles decreases by 90% immediately after LASIK. During the first year after LASIK, subbasal nerve fiber bundles gradually return, although by 1 year their number remains less than half of that before LASIK.

_________________
Broken Eyes

"The price good men pay for indifference to public affairs is to be ruled by evil men." Plato


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 Post subject:
PostPosted: Sun May 04, 2008 10:17 pm 
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Trans Am Ophthalmol Soc. 2005;103:56-66; discussion 67-8.

Long-term corneal keratoctye deficits after photorefractive keratectomy and laser in situ keratomileusis.

Erie JC, McLaren JW, Hodge DO, Bourne WM.
Department of Ophthalmology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.

PURPOSE: To measure changes in keratocyte density up to 5 years after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

METHODS: This was a prospective, nonrandomized clinical trial. Eighteen eyes of 12 patients received PRK to correct a mean refractive error of -3.73 +/- 1.30 D, and 17 eyes of 11 patients received LASIK to correct a mean refractive error of -6.56 +/- 2.44 D. Corneas were examined by using confocal microscopy before and 6 months, 1 year, 2 years, 3 years, and 5 years after the procedures. Keratocyte densities were determined in five stromal layers in PRK patients and in six stromal layers in LASIK patients. Differences between preoperative and postoperative cell densities were compared by using Bonferroni-adjusted paired t tests.

RESULTS: After PRK, keratocyte density in the anterior stroma was decreased by 39%, 42%, 45%, and 47% at 6 months, 2 years, 3 years, and 5 years, respectively (P < .001). At 5 years, keratocyte density was decreased by 20% to 24% in the posterior stroma (P < .05). After LASIK, keratocyte density in the stromal flap was decreased by 22% at 6 months (P < .02) and 37% at 5 years (P < .005). Keratocyte density in the anterior retroablation zone was decreased 18% (P < .005) at 1 year and 43% (P < .005) at 5 years. At 5 years, keratocyte density was decreased by 19% to 22% (P < .05) in the posterior stroma.

CONCLUSIONS: Keratocyte density is decreased in the anterior stroma after PRK and in the stromal flap and the retroablation zone after LASIK for up to 5 years. Posterior stromal keratocyte deficits are first noted at 5 years.

From the full text:

Alternatively, a causal relationship between decreased keratocyte density and decreased innervation after LASIK has been hypothesized.11-13,22 M?ller and coworkers23 documented direct innervation of keratocytes by stromal nerves. A normal stromal keratocyte population may depend on a normal density of corneal nerves. Transplanted corneas, for example, have both keratocyte24 and nerve deficits.22 We recently showed that subbasal nerves were still reduced 21% by 5 years after LASIK, although nerve densities were not significantly different from preoperative densities (Erie JC, et al, ARVO Meeting, 2005, E-abstract 4355). What effect, if any, a reconstituted nerve density has on future keratocyte densities is unknown. It is likely that the epithelium, stroma, and nerves all participate, to varying degrees, in the homeostasis of stromal keratocytes. Their eventual effect on keratocyte density after PRK and LASIK will require longer follow-up.
The clinical significance of a reduced keratocyte population after PRK and LASIK and its effect on the long-term health of the cornea is unknown.

_________________
Bill

"What concerns me is that if the person informing the patient is themselves poorly or inaccurately informed then how on earth can consent ever be truly informed?" Dr. Sarah Smith


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