Goldmann applanation tonometry after myopic photorefractive keratectomy

PURPOSE

To determine the accuracy of applanation tonometry in patients with corneas thinned by photorefractive keratectomy, and to correlate corneal changes with tonometric readings.

METHODS

The intraocular pressure was measured with Goldmann applanation tonometry in 87 patients who underwent photorefractive keratectomy before and 1, 6 and 12 months after treatment. The treatments ranged from -1.5 to -14 diopters (mean=-7.6+/-4.1 diopters) and the fellow eyes were used as controls.

RESULTS

In the treated eyes the intraocular pressure before surgery ranged from 11 to 26 mmHg (mean=17.7+/-2.8 mmHg). One month after surgery it ranged from 5 to 22 mmHg (mean=11.9+/-2.7 mmHg) with a significant underestimation (P=1x10(-33)). Six months after surgery it ranged from 6 to 22 mmHg (mean=12+/-3 mmHg) with a significant underestimation (P=5x10(-30)). Twelve months after surgery it ranged from 8 to 22 mmHg (mean=12.7+/-2.7 mmHg) with a significant underestimation (P=5x10(-31)).

CONCLUSIONS

A correcting factor should be applied when using applanation tonometry to measure intraocular pressure in patients who have undergone PRK.

Non-contact tonometry in patients that underwent photorefractive keratectomy

To determine the accuracy of non-contact tonometry in patients with corneas thinned by photorefractive keratectomy, the authors measured the intraocular pressure with a non-contact tonometer and the corneal thickness with an ultrasonic pachymeter in 47 patients before and 9 months after photorefractive keratectomy. The patients were divided into three groups according to the degree of treatment: group I between 1 and 5 diopters (14 eyes), group II between 6 and 10 diopters (18 eyes), group III between 11 and 15 diopters (15 eyes). In the first group of patients mean intraocular pressure was 16.1 (+/-3.85) mm Hg before surgery, and 13.2 (+/-3.14) mm Hg after surgery with a significant difference (p = 0.0027). In the second group of patients mean intraocular pressure was 16.0 (+/-4.13) mm Hg before surgery and 13.0 (+/-3.0) mm Hg after surgery with a significant difference (p = 0.0045). In the third group of patients mean intraocular pressure was 17.7 (+/-3.8) mm Hg before surgery and 12.4 (+/-2.6) mm Hg after surgery, with a significant difference (p = 0.0005). In conclusion, according to our results, non-contact tonometry needs a correcting factor for measuring the intraocular pressure in patients that underwent photorefractive keratectomy, related to the degree of refractive treatment.

The corneal endothelium 12 months after photorefractive keratectomy in high myopia

PURPOSE

To determine if photorefractive keratectomy with a 193 nm excimer laser could cause human corneal endothelial changes, mainly in high dioptric treatments.

METHODS

18 patients underwent a treatment ranging from 7 to 13 diopters at the corneal apex (mean 10.3 +/- 1.4 SD) with an estimated corneal thinning ranging from 62 to 116 microns (mean 90.7 +/- 12 SD). In these patients a comparison between the number and shape of the corneal endothelial cells has been performed before and 12 months after PRK.

RESULTS

The mean cell density was 2818 +/- 337 mm2, before surgery, and 2894 +/- 301 mm2 after 12 months. The polymorphic index was 79.0 +/- 2.3, before surgery, and 81.0 +/- 5.0 after 12 months with no significant changes (p = 0.16 and P = 0.09, respectively).

CONCLUSIONS

These results show that photorefractive keratectomy does not cause any significant observable damage to the central corneal endothelium up to 12 months after surgery, even in high myopic treatments.

Endothelial cells evaluation two years after photorefractive keratectomy

To evaluate long-term corneal endothelium damages after myopic photorefractive keratectomy (PRK) a morphometric analysis of corneal endothelial cells was performed in 41 patients before and at least 24 months after photorefractive keratectomy. These patients underwent a treatment ranging from -2.5 to -14 dpt with a mean of 8.9 +/- 2.8 dpt at the corneal apex, with an estimated corneal thinning ranging from 23 to 123 microns with a mean of 78 +/- 24.4 microns. Our results showed that the density of endothelial cells ranged from 2,334 to 3,554/mm2 with a mean of 2,819 +/- 351/mm2 before surgery, and from 2,051 to 3,461/mm2 with a mean of 2,774 +/- 330/mm2 after surgery without any significant changes (p = 0.16). The polymorphic index ranged from 58 to 84 with a mean of 77 +/- 5.7 before PRK and from 57 to 89 with mean of 77.7 +/- 7.2 after treatment without any significant changes (p = 0.61). In conclusion, we can state that there is no long-term corneal endothelial damage after PRK even in highly myopic eyes.

Use of a special device for the treatment of overfiltration after glaucoma filtering surgery

BACKGROUND

standardized A and B scan echography were used to look for the possible presence of ciliochoroidal detachment in patients with flat anterior chamber following glaucoma filtering surgery. For this purpose, a scleral shell filled with saline solution was inserted between the lids. As a deepening of the anterior chamber was found in some patients, we planned to utilize these devices for the treatment of flat anterior chambers after glaucoma filtering surgery.

METHODS

16 patients with flat anterior chambers after glaucoma filtering surgery underwent the insertion of a scleral shell filled with saline solution between the lids. The shell was left in place for 15 min.

RESULTS

In all of our patients a deepening of the anterior chamber was achieved. In 5 patients 1 application, in 6 patients 2 applications, in 4 patients 3 applications were needed.

CONCLUSIONS

The advantages of using this procedures are: the procedure is quick; it does not disturb the corneal epithelium; it is cheap; it does not require suturing the conjunctiva; it can be part of the examination of the anterior segment with echography to look for any ciliary body detachment.

Refractive outcome and corneal topographic studies after photorefractive keratectomy with different-sized ablation zones

BACKGROUND

Discrepancies may still occur between planned and actual refractive correction in eyes undergoing photorefractive keratectomy (PRK). The authors have evaluated the use of an enlarged ablation zone.

METHOD

A computerized corneal analysis system has been used to compare the changes of the anterior surface of the cornea and the refractive changes before and 1, 6, and 12 months after PRK in 113 patients (119 eyes) treated with an excimer laser. The patients were divided into two groups: those treated with a mask with a 5-mm window (59 eyes), and those with a new mask with different window openings according to the degree of refraction at the corneal apex, starting from 5 mm in diameter for treatments less than 6.5 diopters (D) and from 7 mm in diameter for higher treatments (60 eyes). In the first group, treatment ranged from -2.5 to -16 D (mean +/- standard deviation. -8.5 +/- 3.24 D); in the second group, it ranged from -1 to -14 D (-7.8 +/- 3.06 D). Treatments were evaluated with a chi-square test.

RESULTS

In the first group of eyes, 46% were within +/-1 D at 1 month, 37% at 6 months, and 39% at 12 months. In the second group of eyes, 73% were within +/-1 D at 1 month, 60% at 6 months, and 58% at 12 months. The comparison between these data and corneal topographic changes shows that both are more stable and predictable with the new mask compared with the 5-mm mask (P = 0.002, 0.02, 0.04, at 1, 6, and 12 months, respectively).

CONCLUSIONS

The use of larger ablation zones improves the predictability and stability of refractive changes.

Macula study with standardized echography

At an early clinical stage, patients with cystoid macular oedema show no significant changes in their vision. This phase is described as angiographic cystoid macular oedema. Echographic macular studies have in the past years shown that the macular thickness is increased in the early stages of cystoid macular oedema. In these patients there was no evidence of cystoid macular oedema with the visual acuity test, B-scan echography and fluorescein angiography. In this paper an echographic macular study by standardized A-scan echography was performed in 537 patients before extracapsular cataract extraction and intraocular lens implantation in posterior chamber (ciliary sulcus). The results showed that this method is very sensitive in detecting patients with high risk of cystoid macular oedema.

Effects on the corneal endothelium six months following photorefractive keratectomy

Photorefractive keratectomy (PRK) with a 193-nm excimer laser has been shown not to destroy endothelial cells in vivo. However, this laser could damage endothelial cell metabolism, and result in damage over a longer term. In this paper, a comparison between the number and shape of corneal endothelial cells has been performed in 25 patients before and 6 months after PRK. These patients underwent treatment with myopic correction ranging from 2.5 to 17 dpt and with an estimated corneal thinning ranging from 25 to 170 microns. No significant changes in the number (p = 0.167) and shape (p = 0.075) of endothelial cells have been found. These results show that there are no long-term damages after PRK even in severely myopic eyes.

First experience with a new echographic contrast agent

The intravenous injection of an ultrasound contrast agent can enhance signals from blood flow. Broad toxicological and pharmaceutical studies in animals confirmed the safety and efficacy of an ultrasound contrast agent made of microparticles of galactose with stabilised microbubbles in watery suspension (SH U 508 A). In this paper 10 patients with different malignant orbital and ocular tumours have been evaluated with an echo colour Doppler machine before and after the injection of SH U 508 A. An enhancement of the Doppler signals in the lesions in different degrees has been detected. This echographic contrast agent seems to be very important not only in the evaluation of vascular lesions, but also in evaluating the effectiveness of radiotherapy in malignant tumours and could spread the echographic indications in several other ophthalmic fields.

Evaluation of corneal thickness and endothelial cells before and after excimer laser photorefractive keratectomy

BACKGROUND

The possible endothelial damage induced by photorefractive keratectomy was investigated in myopic eyes.

METHODS

A morphometric analysis of the endothelial cells was performed in 19 patients before and 2 months after photorefractive keratectomy for the correction of various degrees of myopia. Central ultrasonic pachometry was also recorded at the same examination times.

RESULTS

No significant changes (p = .816) of the endothelial cell density were found between preoperative and postoperative measurements. The pleomorphic index did not show any significant changes after treatment (p = .955). Central corneal thickness was reduced to a various extent (range from 50 microns to 250 microns) according to the amount of myopic correction intended.

CONCLUSIONS

Our preliminary data suggest that photorefractive keratectomy for the correction of myopia does not induce endothelial cell damage, at least in the short term.

Visual function before and after photorefractive keratectomy for myopia

BACKGROUND

To date, Snellen visual acuity and postoperative refraction have been used to evaluate the results of photorefractive keratectomy. However, other parameters, such as contrast sensitivity function and glare, may be affected by refractive surgery and lead to unsatisfactory visual performance. This prospective study is aimed at evaluating the effect of photorefractive keratectomy on contrast sensitivity function and glare.

SUBJECTS AND METHODS

Static contrast sensitivity function, dynamic contrast sensitivity function, and glare sensitivity were evaluated in 22 myopic eyes before as well as 1, 3, and 6 months after photorefractive keratectomy. The eyes tested were divided into three groups, according to the amount of myopia: group I, from -4.00 to -8.00 diopters (D); group II, from -8.25 to -11.00 D; group III, from -11.25 to -20.00 D.

RESULTS

Both static and dynamic contrast sensitivity function at the intermediate spatial frequencies were altered at 1 month after photorefractive keratectomy, with a trend toward recovery at 3 and 6 months postoperatively. Glare sensitivity was not significantly affected by surgery.

CONCLUSIONS

Contrast sensitivity function and glare testing may show abnormalities in the presence of optimal visual and refractive results. These tests may result especially important for the evaluation of new refractive surgical procedures.

Phototherapeutic keratectomy in the treatment of Avellino dystrophy

Avellino corneal dystrophy has rarely been reported in literature. It consists of a combination of granular and lattice dystrophy. Patients may complain of glare and decreased night vision with or without decreased visual acuity, depending on the degree of corneal involvement. Current treatment for this dystrophy includes bandage contact lenses for the erosions or corneal transplant in the case of decreased visual acuity. We describe the first patient with Avellino corneal dystrophy to have been treated with phototherapeutic keratectomy.

An unusual orbital lesion: hepatoma metastatic to the orbit

The authors describe a case of histologically proven orbital metastasis from a hepatic carcinoma in an 85-year-old patient with rapid onset of proptosis and visual loss. The clinical diagnosis of orbital metastatic lesion was established by standardized echography and CT scan. To the best of our knowledge, this is only the third histologically proven case of hepatoma metastatic to the orbit.

Phenotypic variation in combined granular-lattice (Avellino) corneal dystrophy

OBJECTIVE

To describe the phenotypic variation exhibited by members of families with combined granular-lattice (Avellino) corneal dystrophy.

SETTING

We examined 40 patients (age range, 12 to 85 years) from six unrelated families with Avellino corneal dystrophy. This included the first individuals to ever be examined near the presumed site of origin in Italy. In addition, one family was the first to trace its origins to Germany rather than to Italy. We studied the phenotypic expression of the disease in the cornea, visual acuities, subjective complaints, complications, treatment, and histologic condition of these individuals.

RESULTS

The granular stromal lesions reach their mature quantity and size early in life, and appear as either gray and crumb-shaped deposits or superficial with an annular and planar distribution. The lattice component appears gradually, beginning and maturing later in life. The phenotypic variation within families was found to be substantial. Widely variable proportions of lattice and granular changes were found within single sibships. Visual acuities ranged from 20/20 to 20/400. Recurrent corneal erosions were present but infrequent. Subjective complaints included glare and decreased night vision. Penetrating keratoplasty was required in one individual to restore vision. Histopathologic examination revealed typical amyloid and granular deposits. Granular deposits were found replacing Bowman's membrane and extending to the corneal surface. These deposits probably represent the cause of recurrent erosions.

CONCLUSIONS

Combined granular and lattice corneal dystrophy may present with substantial phenotypic variation. The disease can be found in individuals who trace their ancestry to both Italy and Germany, a wider geographic distribution than previously proposed.

A study of sister chromatid exchange and somatic cell mutation in hospital workers exposed to ethylene oxide

To investigate the risks of exposure to ethylene oxide (EO) at current permissible levels and at past higher levels, an inception cohort of sterilizer operators and supervisors from the Central Processing Department (CPD), respiratory therapists, and engineers exposed to EO were identified at the McMaster University Medical Centre. A comparison group from Nutrition Services (NUTR) were matched with the CPD workers on the basis of sex, age, and smoking habit. The present report is based on genetic test results for the 94 CPD and matched NUTR workers only. Statistical analysis based on the mean SCE frequency in the top 5, top 10, and all cells (50 cells scored per individual) and high frequency cells (HFC) based on the 95th percentile for nonsmoking control subjects showed a direct association with current smoking but not with EO exposure. Similarly, statistical analysis of the somatic cell mutation (SCMT) variant frequencies did not demonstrate an association with EO exposure, nor with smoking. Regression analysis indicated that sex was the only other covariate that significantly affected SCE. Age was weakly associated with SCMT. A statistically significant interaction between occupational exposure and smoking habits was observed only for the mean SCE frequency of the top 5 and top 10 cells when the 11 current CPD/NUTR pairs were not included. Thus, this interaction should be interpreted with caution.

Optic nerve involvement in acute lymphoblastic leukemia

Leukemic infiltration of the optic nerve is rare. We describe the diagnostic assessment and the outcome in two adult patients suffering from acute lymphoblastic leukemia with T phenotype. In both cases the leukemic involvement of the eye was observed as an isolated extramedullary relapse followed after several months by hematological relapse. CT and MRI scans were negative, while an A-scan echography of the eye clarified the diagnosis. Early radiotherapy caused recovery of visual acuity in one case. A-scan echography is the most sensitive investigation for the early recognition of ocular localization in acute leukemias.

Echographic and ophthalmodynamometric study in the empty sella syndrome

A group of patients with empty sella syndrome (ESS) and visual field defect with or without visual loss has been examined with standardized echography and ophthalmodynamometric examination. The optic nerve thickness has been evaluated with standardized echography; the pressure of the central retina artery has been evaluated with ophthalmodynamometric examination with or without compression on the external carotid. Our results point out two different pathogeneses in the ESS: vascular defects or irregular endocranial hypertension.

Regulation of starch and sugar levels in tobacco leaves by gibberellic acid

Gibberellic acid (GA3) significantly reduced the level of starch in green leaves of tobacco plants. The total α-amylase activity and the specific activities of α-amylase and invertase were increased by GA3 treatment. Hydrolysis of starch during flue-curing contributed greatly to the increased level of reducing sugars in cured leaf tissue; decreasing the level of starch in green leaves by GA3 effectively lowered the level of reducing sugars after curing.

Formation and occurrence of N-malonylphenylalanine and related compounds in plants

Shoots of barley seedlings when fed D-phenylalanine convert the amino acid to N-malonylphenylalanine. Some N-acetylphenylalanine is obtained at the same time but this may be an artifact of the isolation procedure since it is readily formed by decarboxylation of the malonylphenylalanine. Feeding experiments with the D- and L-isomers of phenylalanine, valine, leucine, isoleucine, tyrosine, tryptophan, alanine, and glutamic acid showed that barley shoots form the malonyl derivative from all the D-isomers whereas little, if any, is formed from the L-isomers. Similar experiments with phenylalanine and leucine isomers, using seven different plant species, showed that the ability to conjugate the D-isomers (but not the L-isomers) was found in all of the plants tested. It was also observed that the ether-soluble acidic conjugates of a variety of amino acids, possibly malonyl derivatives, occur widely throughout the plant kingdom.