Femtosecond laser-assisted implantation of complete versus incomplete rings for keratoconus treatment

Purpose

To compare complete versus incomplete ring implantation for keratoconus correction.

Methods

We investigated 25 eyes of keratoconic patients, of which 15 had femtosecond-assisted MyoRing corneal implantation (Group 1) and 10 had femtosecond-assisted Keraring segments (Group 2). Uncorrected distance visual acuity (UCVA), best corrected distance visual acuity (BCVA), mean K (K_m), sphere, topographic cylinder, and corneal asphericity value (Q-value) were measured in all eyes preoperatively and at 4 weeks postoperatively (1 month).

Results

In Group 1, the K_m change was −6.15±2.16 D, with a mean change in sphere of 4.45±2.18 D and a mean change in refractive cylinder of 2.32±3 D. UCVA change was −0.57±0.273 logarithm of the minimum angle of resolution (LogMAR), BCVA change was −0.2±0.27 (LogMAR), and the Q-value change was 0.43±2.6. In Group 2, the K_m change was −3.15±1.68 D, UCVA change was −0.48±0.37 (LogMAR), BCVA change was −0.09±0.15 (LogMAR), and the Q-value change was 0.5±0.21. Changes in the means did not significantly differ between groups, except for the K_m change, which was significantly greater in Group 1 than in Group 2 (P=0.05).

Conclusion

Both complete ring and ring segment implantation are effective for improving corneal and visual parameters in keratoconus. Complete ring implantation may have a greater flattening effect on the anterior corneal surface.

Changes in retinal nerve fiber layer thickness following mechanical microkeratome-assisted versus femtosecond laser-assisted LASIK

Purpose

To study the influence of the transient elevation of intraocular pressure during suction in laser-assisted in situ keratomileusis (LASIK) on the retinal nerve fiber layer (RNFL) thickness both in microkeratome assisted and femotsecond (FS) LASIK.

Patients and methods

An interventional case series that included 40 eyes suffering from myopia who were candidates for LASIK. All underwent Wave Front Guided LASIK by the same surgeon using the VisX CustomVue platform. A corneal flap was created in 20 eyes using a mechanical microkeratome Moria M2 (MMK), while the IFS IntraLase™ was used in the remaining 20 eyes. Mean suction time was recorded from “Suction ON” to “Suction OFF” time. Optic cube and RNFL thickness analysis using Spectral Domain Optical Coherence Tomography (SD-OCT) Cirrus-HD was completed before, and 1 month after LASIK.

Results

The study included 40 eyes of 20 patients. All were females with mean age 33.5 ± 6.4 years. Mean preoperative spherical equivalent was −3.62 ± 2.31D. Average preoperative RNFL thickness was 94.6 ± 12.1μm in MMK group while the postoperative average thickness was 95.1 ± 11.9 um with no statistically significant difference (P-value: 0.37). Average preoperative RNFL thickness was 108.28 ± 8.4 μm in FS group compared to 108.38 ± 11.2 μm in the postoperative average with no statistically significant difference (P-value: 0.94). Mean “Suction ON” to “Suction OFF” time was 22 seconds in the MMK group compared to 41 seconds in the FS group.

Conclusion

The rise of intraocular pressure during application of suction ring in LASIK surgery does not affect the RNFL thickness as measured by SD-OCT, whether the flap is created by MMK or FS.

Common complications of deep lamellar keratoplasty in the early phase of the learning curve

PURPOSE

To evaluate and record the common complications that face surgeons when they perform their first few series of deep lamellar keratoplasty and measures to avoid these.

SETTING

Dar El Oyoun Hospital, Cairo, Egypt.

METHODS

Retrospective study of the first 40 eyes of 40 patients carried out by two corneal surgeons working in the same center. All patients were planned to undergo a deep anterior lamellar keratoplasty using the big bubble technique. Twelve patients suffered from keratoconus while 28 patients had anterior corneal pathologies. Recorded complications were classified as either intraoperative or postoperative.

RESULTS

Perforation of Descemet's membrane was the most common intraoperative complication. It occurred in nine eyes (22.5%): five eyes (12.5%) had microperforations while four eyes (10%) had macroperforations, three eyes (7.5%) had central perforations, and six eyes (15%) had peripheral perforations. Other complications included incomplete separation of Descemet's membrane and remnants of peripheral stromal tissue. Postoperative complications included double anterior chamber which occurred in four eyes (10%) and Descemet's membrane corrugations. Postoperative astigmatism ranged from 1.25 to 4.5 diopters with a mean of 2.86 diopters in the whole series, but in the six cases with identified residual stroma in the periphery of the host bed, the astigmatism ranged from 2.75 to 4.5 diopters with a mean of 3.62 diopters.

CONCLUSION

Deep lamellar keratoplasty is sensitive to procedural details. Learning the common complications and how to avoid them helps novice surgeons to learn the procedure faster.

Changes in corneal biomechanics following different keratoplasty techniques

PURPOSE

To evaluate corneal biomechanics with the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Depew, NY) after penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK).

SUBJECTS AND METHODS

Sixty-three eyes of 63 patients were included in this prospective comparative study. Patients were divided into 3 groups: the first included 21 eyes of normal subjects (control group); the second included 21 eyes with PK; the third included 21 eyes with DALK. ORA was performed 2 months postoperatively for all patients.

RESULTS

Both mean corneal hysteresis (CH) and mean corneal resistance factor (CRF) were significantly lower in the PK group than both the DALK group and matched controls. No statistically significant difference was found between mean CH and mean CRF between the DALK group and matched controls

CONCLUSION

Corneas after PK have weaker biomechanical properties than normal corneas. DALK preserves the biomechanical strength of the corneas to almost normal values.

Comparison of higher-order aberrations after LASIK using disposable microkeratome 130 and 90 micron heads

PURPOSE

To analyze and compare higher-order aberrations (HOAs) in cases of laser in situ keratomileusis (LASIK) flaps made using the Moria M2 disposable 130-micronm head with those made using the 90-micronm head.

METHODS

Consecutive prospective comparative clinical trial. Ninety-four consecutive eyes of 48 patients were enrolled in this study. They were divided into two equal groups of 47 eyes that underwent wavefront-guided LASIK using VISX CustomVue (VISX, Santa Clara, CA) system. Corneal flap was created using the disposable Moria M2 130 micronm in the first group and the 90 micronm head in the second one. All patients were followed up for 6 months. Wavefront aberrations were measured at baseline, 1 month, and 6 months after surgery using the WaveScan (VISX Inc.) aberrometer. Root mean square (RMS) of HOAs, coma, and spherical aberration (SA) values were analyzed and compared in the two groups.

RESULTS

At 6 months, values of RMS of HOAs, coma, and SA obtained from the 130-micronm head group were 0.32+/-0.10 micronm, 0.20+/-0.11 micronm, and 0.18+/-0.08 micronm, respectively. Values of RMS of HOAs, coma, and SA obtained from 90-micronm head group were 0.33+/-0.12 micronm, 0.19+/-0.10 micronm, and 0.15+/-0.08 micronm, respectively. Analyzing the data obtained revealed no statistically significant differences between the two groups. In each group, there was a significant decay of higher-order RMS and coma values from 1 month to 6 months.

CONCLUSIONS

HOAs following use of Moria M2 disposable 90 micronm head are similar to those arising following use of the 130 micronm.

Fluorescein-assisted viscodissection for easier phacoemulsification

TITLE

Fluorescein-assisted viscodissection for easier phacoemulsification.

SETTINGS

Department of Ophthalmology, Cairo University.

PURPOSE

The description of a new surgical technique to help overcome difficulties in the learning curve of phacoemulsification.

METHODS

A mixture of Fluorescein 0.25% and methyl cellulose 0.25% is used for hydrodissection. Standard phacoemulsification is then continued until the initial groove reaches the plane between the lens cortex and the capsule when the fluorescein flows towards the anterior chamber in a Green Smoke. This sign indicates a proper depth for attempting to crack the nucleus into two halves.

Combined lidocaine 1% and hydroxypropyl methylcellulose 2.25% as a single anesthetic/ viscoelastic agent in phacoemulsification

PURPOSE

To evaluate the use of a mixture of hydroxypropyl methylcellulose 2.25% (HPMC) and lidocaine 1% (final concentrations) as a single viscoelastic/anesthetic agent to achieve proper anesthesia and viscoelastic properties during phacoemulsification.

SETTINGS

Department of Ophthalmology, Cairo University, Cairo, Egypt.

METHODS

This prospective randomized study comprised 70 eyes having routine phacoemulsification. Patients had the HPMC-lidocaine mixture (n = 35) or pure HPMC 2.25% (n = 35) injected before capsulorhexis and again before intraocular lens implantation. The results were evaluated by a pain/discomfort score postoperatively.

RESULTS

The difference in medians of the overall intraoperative pain/discomfort scores between the 2 groups was not statistically significant. However, mild pain/discomfort was reported by 60.0% in the pure HPMC group and by 31.4% in the HPMC-lidocaine mixture group. Moderate pain/discomfort was reported by 28.6% and 5.7%, respectively. The difference between the 2 groups was statistically significant (P =.001).

CONCLUSION

The use of a mixture of HPMC 2.25% and lidocaine 1% rather than a regular viscoelastic agent resulted in clinically and statistically significantly reduced pain/discomfort during phacoemulsification.

Evaluation of factors influencing the marginal bone stability around implants in the treatment of partial edentulism

BACKGROUND

The original protocol of Brånemark to achieve predictable osseointegration for oral implants has substantially been modified. One may question whether results are influenced by those modifications, especially for the long-term prognosis.

PURPOSE

The goal of the present study was to investigate the impact of those parameters that deviate from the original protocol as defined by P-I Brånemark.

MATERIALS AND METHODS

In this study, 246 patients with 263 fixed partial prostheses supported by 668 Brånemark implants were followed from 1 to 15 years (mean: 6.3 yr). Radiographs were taken at the time of abutment connection, at 3 to 6 months, at 12 months, and then every 3 years. The bone level was rated mesially and distally from the implants on a total of 2588 radiographs.

RESULTS

A positive relation between abutment length and marginal bone level was found (p > .0001). The maxilla (p = .03), porcelain (p = .007), long abutments (p = .008), and regular-sized diameter implants (p = .001) all exhibited more bone loss in the first 6 months. After 6 months, only long implants showed more bone loss (p = .03).

CONCLUSIONS

Overall, the marginal bone level remained stable around Brånemark implants, never surpassing 2.2 mm, even after 15 years. Although longer implants lost more bone over time, this has to be interpreted with respect to higher resorption rates in less resorbed jaws.

Hydroxylations and methylations of quercetin, fisetin, and catechin by Streptomyces griseus

Preparative-scale biotransformation of quercetin (1), fisetin (7), and (+)-catechin (12) with Streptomyces griseus (ATCC 13273) resulted in the isolation and characterization of nine known hydroxylated and/or methylated (2--6, 8, 9, 11, 13a) metabolites and two previously unknown (10 and 14) metabolites. S.griseus catalyzed aromatic hydroxylations of rings A and B of quercetin and fisetin. Mono- and dimethoxy ring-B metabolites were obtained with all three substrates. Methylation appeared to occur only when catechol functional groups were present. Metabolite structures were established by FABMS, EIMS, and 1D and 2D NMR analysis.

Within-subject comparison between connected and nonconnected tooth-to-implant fixed partial prostheses: up to 14-year follow-up study

PURPOSE

This long-term follow-up study aimed to compare the outcome of fixed prostheses supported by teeth and implants and by freestanding implants only.

MATERIALS AND METHODS

From prosthesis insertion up to 14 years (mean 6.5 y), 18 patients were followed. Implant-supported prostheses with and without tooth connection were compared within the same jaw. The tooth-implant prostheses were supported by 30 implants and 30 teeth, and the freestanding prostheses were supported by 48 implants. Implant outcome, marginal bone stability, and mechanical complications were recorded.

RESULTS

Neither implant mobility nor fractures of any component of the implants were observed. No prosthesis complications were observed, and the same applied for crown cement failure and intrusion of teeth. Only one periapical lesion was detected at the first follow up. The annual change of the marginal bone level around connected and freestanding implants did not differ significantly. The mean marginal bone loss (over the 2 groups) for the first 6 months amounted to 1.08 mm. After the first 6 months, an annual marginal bone loss of 0.015 mm was observed. There was no difference between the 3 connection types (single implant connected to single tooth, multiple implants and/or multiple teeth connected with single connector, and multiple connectors) for the first 6 months or thereafter. The marginal bone loss (over the 3 groups) for the first 6 months was 1.15 mm. After the first 6 months, the annual bone loss (over the 3 groups) amounted to 0.015 mm.

CONCLUSION

Based on the results of this study, splinting teeth with implants for implant-supported fixed prostheses did not affect the long-term outcome in comparison to freestanding implants.

Relationship Between Anterior Chamber Depth, Refractive State, Corneal Diameter, and Axial Length

PURPOSE

Phakic intraocular lenses are being used increasingly to correct refractive errors. We studied the relationship between anterior chamber depth, refractive state of the eye, spherical equivalent refraction, axial length of the globe, corneal diameter, and keratometry.

METHODS

Two hundred eleven eyes of 211 patients were enrolled. All eyes underwent the same protocol with a complete ocular examination that included slit-lamp microscopy, intraocular pressure, objective and subjective refraction, calculation of the spherical equivalent refraction, corneal pachymetry, anterior chamber depth, axial length of the globe, and keratometry. All results were analyzed statistically using SPSS statistics software. Correlations between different parameters were studied using the Pearson correlation test.

RESULTS

The anterior chamber depth was found to correlate significantly with both the average corneal diameter and the axial length of the globe (0.744, 0.531, P < .01) and was also found to correlate through an inverse relation with both age and spherical equivalent refraction (-0.391, -0.623, P < .01). Corneal thickness and keratometric power did not correlate with the anterior chamber depth.

CONCLUSION

Most parameters (axial length, corneal diameter, spherical equivalent refraction, patient age) affected anterior chamber depth and should be considered carefully when planning refractive procedures that employ phakic intraocular lenses.

Novel isoflavone, cinnamic acid, and triterpenoid glycosides in soybean molasses

Seven known isoflavones, genistein (4), daidzein (5), glycitein (6), formononetin (7), genistin (8), daidzin (9), and glycitein 7-O-beta-D-(6' '-O-acetylglucopyranoside) (10), ferulic acid, and two known saponin glycosides, soysaponin I (14) and soysaponin A2 (15), were isolated from soybean molasses. Several new compounds were also isolated and identified, including three isoflavones (1-3), two cinnamic acid ester glycosides (11) and (12), and a new saponin hexaglycoside (13). The structures of the new compounds were established on the basis of spectral data interpretation.

Intraspecific ITS polymorphism in Scutellospora castanea (Glomales, Zygomycota) is structured within multinucleate spores

Polymorphism of the internal transcribed spacers (ITS) of the ribosomal DNA in Scutellospora castanea (Glomales, Zygomycota) and its organization among spores were evaluated. Polymerase chain reaction (PCR) amplification with ITS1/ITS4 primers yielded several fragments of different lengths, even from single spores. Fragments produced from multisporal DNA were cloned and grouped into 6 ITS types by PCR-RFLP and sequence analysis. Five type-specific primers were designed. Spores were then analyzed by PCR and amplification profiles revealed that they were qualitatively different one from another due to the presence or absence of some ITS types. Intrasporal segregation of ITS variant length types was also shown, by PCR experiments, utilizing diluted fractions of nuclear suspensions from single spores. The results demonstrate the mainly multikaryotic condition of the spores of S. castanea.

rDNA units are highly polymorphic in Scutellospora castanea (glomales, zygomycetes)

The ribosomal DNA (rDNA) units in the glomalean zygomycete fungus Scutellospora castanea were analyzed. Dot-blot assays allowed an estimation of 75 copies per genome. After constructing a genomic library in a phage lambdaEMBL3 vector, 13 rDNA clones were screened and explored. PCR experiments confirmed their nature and allowed homologous probes to be obtained. Restriction-fragment length polymorphism (RFLP) analysis and hybridizations with 18 s and 25 s probes allowed their grouping into nine families. The 18 s gene from these 13 clones was partially sequenced. The resulting 550 bases sequences were analyzed, and a phylogenetic tree was inferred. This revealed that two clones contain one highly divergent rDNA family (rUSc1) by comparison with other known 18 s sequences from the database. A phylogenetic tree was constructed with the entire 18 s sequences of rUSc1, rUSc3 and those of seven species representative of the glomalean fungi, Glomus, Entrophospora, Acaulospora, Scutellospora and Gigaspora. This tree confirmed that the rUSc1 sequence is the neighbor of 18 s sequences from Glomus (Glomineae), while rUSc3 remained in the group of the Gigaspora and Scutellospora (Gigasporineae). A specific primer, rUSc1-1, was generated from the ITS region of rUSc1, and used for PCR amplification from single spores, depicting the presence of rUSc1 in the genome of S. castanea at a lower frequency than other units.

Gmelinosides A-L, twelve acylated iridoid glycosides from Gmelina arborea

Besides the known iridoids 6-O-alpha-L-rhamnopyranosylcatalpol (1), 6-O-(3"-O-trans-feruloyl)-alpha-L-rhamnopyranosylcatalpol (14), 6-O-(2"-O-acetyl-3", 4"-O-di-trans-cinnamoyl)-alpha-L-rhamnopyranosylcatalpol (15) and the known phenylpropanoid glycosides verbascoside (acteoside) and martynoside, 12 new acylated iridoid glycosides named gmelinosides A-L (2-13) have been isolated from the leaves of Gmelina arborea. These compounds were structurally characterized using a variety of spectral methods.

Base composition of DNA from glomalean fungi: high amounts of methylated cytosine

Glomales (Zygomycetes) are obligate fungal symbionts of roots of land plants and form arbuscular mycorrhiza. Sporal DNA of 10 isolates belonging to nine species was purified and the base composition was determined by RP-HPLC. Base composition fell in a narrow range between 30 and 35% G + C. A high amount of methylated cytosine (mC) accounting for 2-4% of the total nucleotides was found in all taxa. The DNA melting profile was defined for Scutellospora castanea. It corresponded to 32% G + C, and the shape of the denaturation curve suggested a heterogeneity in the GC content within the fungal genome. Knowledge of GC contents and variations between taxa are essential for evaluating nuclear DNA content using fluorimetric methods, and high proportions of mC/C + mC in the genomes of glomalean fungi could reflect the existence of repeated DNA families. Results are discussed in relation to data for other fungi and eukaryotes.

Characterization of a highly repeated DNA sequence (SC1) from the arbuscular mycorrhizal fungus Scutellospora castanea and its detection in planta

A highly repeated DNA sequence from the genome of an arbuscular mycorrhizal fungus has been isolated and characterized. This 1,202-bp sequence (SC1) represents about 0.24% of the Scutellospora castanea genome, estimated to be 1 pg by flow cytometry. The sequence was shown to be a Scutellospora-specific probe in Southern blots and dot blot hybridizations. After complete sequencing of SC1, PCR primers were generated and used to amplify a 907-bp fragment from spores of S. castanea or from colonized Allium porrum roots. No amplification products were obtained with DNA from either spores or mycorrhizal root of other species of arbuscular mycorrhizal fungi. These primers were sufficiently specific for unequivocal detection of S. castanea in planta.

Inerminosides A1, C and D, three iridoid glycosides from Clerodendrum inerme

Three new iridoid biglycosides, inerminosides A1, C and D were isolated from the leaves of Clerodendrum inerme and their structures were established as 2'-O-(beta-D-apiofuranosyl)-mussaenosidic acid, 2'-O-[5"-O-(8-hydroxy-2,6- dimethyl-2(E)-octenoyl)-beta-D-apiofuranosyl]-gardoside and 2'-O-[5"-O-(p-hydroxy-benzoyl)-beta-D-apiofuranosyl]-mussaenosi dic acid, respectively.

Inerminosides A and B, two novel complex iridoid glycosides from Clerodendrum inerme

The leaves of Clerodendrum inerme have yielded two new iridoid biglycosides which have been characterized as 2'-O-[5"-O-(8-hydroxy-2,6-dimethyl-2(E)-octenoyl)-beta-D-apiofuranosy l]- mussaenosidic acid (inerminoside A) [1], and 2'-O-[5"-O-(8-hydroxy-2,6-dimethyl-2(E),6(E)-octadienoyl)-beta-D- apiofuranosyl]-8-epi-loganic acid (inerminoside B [2]), respectively. Structure elucidation was carried out both chemically and spectroscopically.

Osteogenesis in composite grafts of allogenic demineralized bone powder and porous hydroxylapatite

This study evaluated the osteoinductive capabilities of porous hydroxylapatite (PH) and the tissue response following intramuscular implantation of PH alone or in combination with demineralized bone powder (DBP). Six rhesus monkeys each received the implants in three separate soft tissue pockets created in the thoracic region. The implants consisted of 2 cc of either PH alone or DBP alone, or a 1:1 combination of DBP and PH. Two animals were killed at 2 weeks, two at 4 weeks, and two at 12 weeks postimplantation. Histologically, bone formation was seen in the DBP mixed with PH and in the DBP group as early as 4 weeks postimplantation; bone was also occasionally observed within the pores of the PH particles. The PH alone showed no evidence of formation of bone and the material was surrounded by a thick layer of fibrous tissue. It was concluded that PH is not osteoinductive, but can act as a scaffold for growth of bone, and that when mixed with an osteoinductive material, it allows for formation of bone within the implant.

Effects of preservation on the osteoinductive capacity of demineralized bone powder allografts

Demineralized bone powder (DBP) has repeatedly been shown to serve as an osteoinductive material. The aim of this study was to investigate the effects of different methods of storage of DBP on its osteoinductive property. Forty-five Long Evan rats were used in this study. Twenty rats were used as donors; the diaphyses of their femoral bones were used for the preparation of DBP. The DBP was divided into four portions that were either lyophilized or frozen at -70 degrees C, -4 degrees C, or kept at room temperature (25 degrees C). All samples were stored under the specified condition for six months. At the time of implantation, fresh DBP was prepared and used as a control. Twenty-five rats were divided equally into five groups. Each group received an implant of either one of the differently preserved and stored samples of DBP or fresh DBP. The animals were killed 60 days following implantation. The implants were excised and processed to obtain 5 micron thick decalcified sections and 3 micron thick undecalcified sections. Semicomputerized histomorphometry was used for the quantification of the newly-formed bone in each implant. Newly-formed bone was detected in all experimental and control groups and there were no statistically significant differences between the various groups. It was concluded that DBP retains its osteoinductivity after lyophilization or preservation at -70 degrees C, -4 degrees C, and 25 degrees C for a period of up to six months, and that the different methods of preservation did not significantly affect the amount of the induced newly-formed bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Osteoinduction in young and old rats using demineralized bone powder allografts

The process of inducing differentiated and undifferentiated cells to become osteogenic using demineralized bone powder (DBP) is a well-known phenomenon in developmental biology. The aim of this study was to examine whether age has an effect on the process of bone induction. DBP was implanted in the subcutaneous thoracic tissue of young rats (28-56 days) and old rats (14 months or older), and the animals were examined seven, 12, 20, and 60 days after implantation. The amount of newly induced bone in the implant was quantitatively measured using histomorphometry and 45Ca uptake. Undecalcified and decalcified specimens were processed for histologic examination using several stains that demonstrate osteoid. Both the young rats and the old rats formed bone in response to the DBP implants. In old animals the induced bone appeared to be less in quantity, it formed at a slower rate, and it exhibited less bone marrow cellularity than did the bone in young animals.

Osteoinduction in rhesus monkeys using demineralized bone powder allografts

This experiment tested the osteoinductivity of demineralized bone powder (DBP) in nonhuman primates. Six DBP implants were implanted subcutaneously close to the pectoralis major muscle in each of four rhesus monkeys. Excisional biopsies were obtained 20, 40, and 72 days after implantation and were processed for light and electron microscopy. Decalcified and undecalcified sections of the implants were studied. Large numbers of undifferentiated mesenchymal and fibroblast-like cells were observed around and within the DBP matrix particles on day 20. Cartilage formation was also evident at that time and had increased by day 40, when chondroid bone also appeared. By day 72, the implants showed mature (lamellar) and immature (woven and chondroid) bone and bone marrow formation. Areas of DBP that were incorporated within the induced bone contained empty lacunae and stained similarly to mineralized bone. It was concluded that allogenic DBP can induce bone formation in monkeys. The results justify the use of DBP as a bone-banked material to induce bone formation in humans.