Outcomes of different lines of keratoconus management in a tertiary eye center in north China.

AIM: To evaluate the treatment selections and outcomes of keratoconus and discuss the grading treatment of keratoconus. METHODS: Medical records of 1162 patients (1863 eyes) with keratoconus treated with rigid gas permeable (RGP), corneal collagen crosslinking, and keratoplasty were reviewed. The patients were grouped according to the CLEK Study. The advanced group was further divided into a <60 D group and >60 D group. The best-corrected visual acuity (BCVA) and topographic data before and after treatment were recorded. RESULTS: In the 761 eyes with steep K<52 D, nonsurgical management accounted for 83.4%, while in the 735 eyes with steep K>60 D, surgical management accounted for 90.6%. A total of 618 eyes had improved BCVA at the final follow-up point (>18mo, P<0.001). When steep K was <52 D, the BCVA in the RGP group was better than those with lamellar keratoplasty (LKP; P=0.028). When steep K was >52 D, the BCVA and topographic astigmatism outcomes showed no differences among the treatment groups. When steep K was >60 D, the BCVA in eyes treated with LKP was worse than those with steep K<60 D (P=0.025). The incidence of steep K progression in the RGP group was higher in advanced group (20.0% vs 10.8%, P=0.019). The probability of future keratoplasty in RGP was higher in advanced group (14.8% vs 7.0%, P=0.027). The incidence of steep K progression in the corneal collagen crosslinking (CXL) group was higher in advanced group (32.3% vs 8.5%, P=0.007). Multivariate logistic regression revealed the following related factors for treatment options: steep K [odds ratio (OR)=1.208, 95%CI: 1.052-1.387], TA (OR=1.171, 95%CI: 1.079-1.270), and TCT (OR=0.978, 95%CI: 0.971-0.984). The level of steep K, TA, and TCT all relates to the treatment choices of both keratoplasty and non-keratoplasty, while steep K provided the highest diagnostic accuracy (AUC=0.947, P<0.001). CONCLUSION: Steep K is an important grading treatment indicator. When steep K is <52 D, RGP lenses should be recommended. It is the best time for LKP when the steep K ranges from 52 to 60 D.

Comparison of long-term results after manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty for keratoconus.

AIM: To compare long-term postoperative outcomes of manual and femtosecond assisted corneal trephination in deep anterior lamellar keratoplasty (FS-DALK) for keratoconus. METHODS: In the retrospective study, 17 consecutive eyes that underwent vertical side cut incision FS-DALK and 22 eyes that underwent trephine incision DALK were collected over a 2-year period. Main measurements included postoperative uncorrected-visual acuity (UCVA), corrected distance visual acuity (CDVA), refractive sphere and cylinder, manifest refraction spherical equivalent (MRSE), flat and steep corneal keratometry (K1 and K2), endothelial cell density (ECD), and time of epithelium healing and suture removal. RESULTS: Groups were comparable for diagnosis and preoperative visual acuity. Follow-up averaged 23mo (range, 12-36mo). At 12mo, the mean UCVA was better in the manual-DALK group (P=0.039), and the refractive sphere was lower in the FS-DALK group (P=0.040). MRSE between groups differed at 1, 6, and 12mo postoperatively (P=0.047, 0.025, 0.042, respectively). Mean CDVA, cylinder, K1, K2, corneal astigmatism, ECD, and time of epithelium healing were similar between groups. Stability of MRSE, ECD, and K1 returned sooner after FS-DALK. Initial loosened suture removal time was earlier in the manual-DALK group (P=0.042) while complete suture removal time was similar (P=0.122). CONCLUSION: Manual and femtosecond assisted corneal trephination in DALK are options for advanced keratoconus. FS-DALK do not result in improved visual acuity but it is more stable during the follow-up period. FS-DALK in the present form show limited benefit, so surgical design and parameters still need to be optimized and explored.

Correlation of basic indicators with stages of keratoconus assessed by Pentacam tomography.

AIM: To evaluate the diagnostic efficiency of basic indicators and find characteristic indicators for keratoconus (KC) at adjacent stages, and to assess the progression pattern of KC. METHODS: One hundred and eight (41 subclinical, 40 moderate, and 27 severe) keratoconic patients (108 eyes) and 105 myopic patients (105 eyes) as controls were recruited in this prospective, comparative case series study. Pentacam topography was performed. Receiver-operating-characteristic curves were used to get the characteristic indicators. RESULTS: The most efficient distinguishing index between the subclinical KC and the controls was posterior elevation value (PEV, AUC=0.882), with the highest specificity being 93.8%. Corneal thickness (AUC=0.852) and posterior inferior-superior value (I-S) ranked second and third (AUC=0.776). When KC became moderate, PEV remained to be of the highest diagnostic efficiency (AUC=0.988), followed by the anterior elevation value (AUC=0.986) and other parameters of anterior surface. The diagnostic value increased significantly in the anterior curvature indices (all AUC>0.900) and appeared in the anterior best fitting sphere radius (AUC=0.919) when KC developed into the severe stage. CONCLUSION: In the subclinical stage of KC, PEV, thickness, and posterior I-S had important diagnostic values, and elevation values remained most efficient when KC developed to the moderate stage. The anterior curvature indices were most characteristic when KC became severe. KC first appeared in the inferior cornea of posterior surface, but the feature of protrusion formed at the moderate stage.

Observation of magnetic field effects on transient fluorescence spectra of cryptochrome 1 from homing pigeons.

Cryptochromes are suggested to be involved in the bird magnetoreception based on the radical pair mechanism (RPM), a well established theory of weak magnetic field effects on chemical reactions. Two members of cryptochrome/photolyase family were found to respond to magnetic field, however, no direct responses of bird cryptochrome to magnetic field as weak as the Earth's magnetic field have been obtained so far. In this study, we used transient fluorescence spectroscopy to characterize the weak magnetic field effects of bird cryptochromes. To do this, we cloned the cryptochrome 1 gene (clCRY1) from the retina of homing pigeons (Columba livia), expressed it in insect Sf9 cells and analyzed the transient fluorescence of purified clCRY1 by application of 45-300 µT magnetic fields. The flavin adenine dinucleotide (FADox ) and glucose oxidase (GOD) in PBS buffer were set as controls which could be excited by light to generate radicals, but would not be sensitive to magnetic field. We observed that the transient fluorescence spectra of clCRY1 were sensitive to the applied magnetic field at room temperature. Our result provides a new proof of the cryptochrome-based model of avian magnetoreception in vitro.

[Comparison of Pentacam and OrbscanII systems for the diagnosis of keratoconus suspects].

OBJECTIVE: To compare the sensitivity of Pentacam and OrbscanII and to analyze the morphology characteristic of topography in normal eyes and different stages of keratoconus, to provide the basis for early screening of keratoconus suspects. METHODS: One hundred and ninety six normal eyes, 50 eyes with keratoconus suspect and 73 eyes with clinical keratoconus were enrolled. The changes of corneal anterior/posterior curvature, best fitting sphere (BFS). Inferior-Superior value (I-S) (3 mm and 5 mm), classification of elevation maps and corneal thickness were measured. RESULTS: There were significant differences including posterior curvature, anterior/posterior BFS, elevation value and corneal thickness in normal eyes between the data measured by these two different instruments, values obtained by Pentacam were less than those by Orbscan. Concerning the elevation maps pattern, the progressively decreasing pattern was dominant in Pentacam with normal eyes and keratoconus suspects, with the progressively increasing pattern accounting for 14.4% (28/196) and 20.0% (10/50) respectively in anterior surface, and 2.0% (41/96) and 26.0% (13/50) in posterior surface. The progressively increasing pattern was in dominant with clinical keratoconus, accounting for 91.7% (67/73) and 94.5% (69/73) respectively in anterior and posterior surface. Progressively increasing pattern in Orbscan was presented in 80.4% (165/196) normal eyes and suspected or clinical stage keratoconus. As to the receiver-operating-characteristic (ROC) curves and cutoff value, Orbscan I-S value (3 mm and 5 mm) of anterior and posterior surface was sensitive for the diagnosis of keratoconus suspects, with the cutoff value of anterior and posterior 5 mm I-S at 1.15 D and 0.65 D, respectively. In addition to the sensitivity of I-S values in Pentacam, the elevation value of anterior and posterior surface also displayed important diagnostic meaning. The cutoff of anterior, posterior elevation values was 4.5 µm and 7.5 µm, respectively. CONCLUSIONS: Numerous measured indicators revealed obviously difference between the two instruments in normal eyes, with slightly smaller values in Pentacam. In addition to I-S values, pattern changes and elevation values in elevation map of Pentacam represent remarkable advantages for the screening of keratoconus suspects. There is an incremental risk of corneal ectasia in the increasing pattern of elevation map.